To ensure that the variables creditAmount and debitAmount cannot change once assigned, the final keyword should be used.
Option B: Use the final keyword and assign its value in the class constructor.
Declaring a variable as final allows it to be assigned once.
Assigning the value in the constructor is acceptable for instance variables.
Option D: Use the final keyword and assign its value when declaring the variable.
Assigning the value at declaration ensures it cannot be changed later.
Why Not Other Options:
Option A: Using static with assignment in the constructor is invalid because static variables belong to the class, not instances.
Option C: Using static and assigning in a static initializer doesn't prevent reassignment unless final is also used.
Reference:
Final Variables:
"You can declare instance variables as final. A final variable can only be assigned a value once, either when you declare it or in the constructor."
- Apex Developer Guide: Classes, Objects, and Interfaces

Tooling API:
The Tooling API provides programmatic access to manage tests and other metadata in the org.
It can execute test classes or methods remotely.
Developer Console:
The Developer Console is a built-in Salesforce tool to execute Apex tests, debug logs, and more.
Allows developers to execute tests interactively.
B). Metadata API: Used for managing metadata, not for running tests.
C). Bulk API: Used for data operations, not related to testing.
References:Tooling API Overview:https://developer.salesforce.com/docs/atlas.en-us.api_tooling.meta
/api_tooling/
Testing with Developer Console:https://help.salesforce.com/s/articleView?id=sf.code_dev_console_test.htm

* A. 75% Test Coverage: Salesforce mandates that 75% of all Apex code must be covered by tests to be deployable to production.
* D. Trigger Coverage: Each Apex trigger must have at least one line of test coverage to ensure it is properly tested.

Understanding the Scenario:
Trigger Definition:
trigger myTrigger on Contact (before insert) {
MyClass.myStaticMethod(trigger.new);
}
Test Class:
The test method calls MyClass.myStaticMethod directly.
Achieves 81% overall code coverage.
The trigger is not invoked during the test.
Key Points:
Code Coverage Requirements:
Minimum 75% Coverage: To deploy Apex code to production, all Apex classes and triggers must have at least 75% overall code coverage.
Trigger Coverage Requirement: All triggers must have some code coverage, meaning they cannot have 0% coverage.
Conclusion: Incorrect.
Option C:
Statement: The deployment fails because the Apex trigger has no code coverage.
Conclusion: Incorrect.
Best Practices:
Always Test Triggers: Ensure that your test methods perform operations that fire the triggers.
Example:
@isTest
public class MyTriggerTest {
static testMethod void testMyTrigger() {
Contact testContact = new Contact(LastName = 'Test');
insert testContact;
// Additional assertions can be added here
}
}
Use Assertions: While not causing deployment failure due to code coverage, assertions help validate that the code behaves as expected.
Reference:
Apex Developer Guide - Code Coverage
Deployment Guidelines
Implications for the Scenario:
Trigger Coverage:
Since the test method does not perform any operations that would fire the trigger (e.g., inserting a Contact record), the trigger myTrigger has 0% code coverage.
Overall Coverage:
Even though the classes achieve 81% coverage, the trigger's lack of coverage affects the deployment.
Deployment Outcome:
Deployment Fails: Because the trigger has 0% coverage, the deployment fails regardless of the overall coverage percentage.
Option Analysis:
Option A:
Statement: The deployment fails because no assertions were made in the test method.
Conclusion: Incorrect.
Option B:
Statement: The deployment passes because both classes and the trigger were included in the deployment.
Conclusion: Correct.
Option D:
Statement: The deployment passes because the Apex code has the required 75% code coverage.