When deploying Apex code to a production environment, certain requirements must be met regarding test coverage and annotations.
Option B: Apex classes must have at least 75% code coverage org-wide.
Correct Requirement.
Salesforce requires that all Apex classes and triggers have a combined code coverage of at least 75% before deployment to production.
This means that, across all Apex code in the org, at least 75% of the code must be covered by test methods.
Every trigger must have some test coverage, even if the overall code coverage is above 75%.
Specifically, triggers must have at least 1% code coverage.
Test methods should be annotated with @isTest.
However, it's not mandatory that all methods in a test class use @isTest; helper methods within test classes can be private or public methods without the annotation.
Only the test methods themselves need the @isTest annotation.
The testMethod keyword is deprecated but still supported.
The preferred approach is to use the @isTest annotation.
Using testMethod is not recommended for new code.
Reference:
Code Coverage Requirement
Option D: At least one line of code must be executed for the Apex trigger.
Correct Requirement.
Trigger Coverage Requirement
Options Not Suitable:
Option A: All methods in the test classes must use @isTest.
Partially Correct.
Defining Test Methods
Option C: Test methods must be declared with the testMethod keyword.
Outdated Practice.
Deprecated testMethod Keyword
Conclusion:
The two factors the developer must take into account are B (75% code coverage org-wide) and D (At least 1% coverage for triggers).
These are mandatory requirements for deploying Apex code to production.