A developer must create a way for external partners to submit millions of leads into Salesforce per day. How should the developer meet this requirement?

A company has a custom object, Sales Demo Request, that has a lookup to an Opportunity. It is required that a Sales Demo Request record be created when an Opportunity's Probability is greater than 50%. What is the optimal way to automate this?

What should a developer use to query all Account fields for the Acme account in their sandbox?

A company wants to run different logic based on an Opportunity's record type. Which code segment handles this request and follows best practices?
A)

B)

A developer has created a Team Member sObject that has a Master-Detail relationship to a Project sObject and a Lookup relationship to the User sObject. The developer must ensure that a User listed on a Team Member record has Read-Write access to the parent Project record.
How can the developer accomplish this if the Project sObject has a Private sharing model and thousands of Project records?