When adding memory, under which rare circumstance would you possibly need to perform a BIOS upgrade?

A.
When there is an available BIOS upgrade that would allow for a greater amount of system RAM to be added.

B.
Whenever the BIOS does not support the new memory size that you want to install.

C.
When the BIOS recognizes that compatible RAM has been installed.

D.
All of the above.

Explanation:
Performing a BIOS upgrade would be the solution if there is an available BIOS upgrade that would allow for a greater amount of system RAM to be added.
Incorrect Answers:
B:
Upgrading the BIOS does not mean that it will automatically support the new memory size that you want to install. To support a memory size, there must be an available BIOS upgrade that caters for it.
C: You do not need to upgrade the BIOS when it recognizes that compatible RAM has been installed. A, BIOS upgrade could though possibly be the solution if the BIOS fails

to recognize that compatible RAM has been installed.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 390-391.