Which two queries can a developer use in a Visualforce controller to protect against SOQL injection vulnerabilities? Choose 2 answers

Given the following Apex statement:

What occurs when more than one Account is returned by the SOQL query?

A platform developer needs to write an apex method that will only perform an action if a record is assigned to a specific record type. Which two options allow the developer to dynamically determine the ID of the required record type by its name? Choose 2 answers

A developer creates a new Apex trigger with a helper class, and writes a test class that only exercises 95% coverage of new Apex helper class. Change Set deployment to production fails with the test coverage warning: "Test coverage of selected Apex Trigger is 0%, at least 1% test coverage is required" What should the developer do to successfully deploy the new Apex trigger and helper class?

A large corporation stones Orders and Line Items In Salesforce for different lines of business. Users are a.. see Orders across the entire organization, but, for security purposes, should only be able to see the Line If Orders in their line of business.
Which type of relationship should be used between Line Items and Orders?