Answer:

B.×64 bit is the most recommended for computers with 4GB and above ram.

Explanation:

32 bit Windows can only access up to 3.7GB of memory, so on a system with 4GB of RAM memory, the extra memory can’t be accessed by the operating system, Windows, so it only becomes useful for the video card.

Depending on what programs you’re using or doing on the system, one might be better suited to you than the other, but there’s also another problem I didn’t mention. In order to run Windows 64 bit, the system's processor needs to be a 64 bit model and not a 32 bit model. You can install and run the 32bit Windows on a 64bit processor, but you can’t run a 64bit operating system on a 32bit processor. Even though new systems these days are all using a 64bit processor, there are still many, many systems out there equipped with a 32bit processor, and those will not be able to run 64bit Windows unless the processor is upgraded (if it even can be on some specific systems).