Which part of the microscope should you use to carry it?

a. the stage

b. the eyepiece

c. the focus knobs

d. the arm

Is it the arm?

Your answers aren't complete. A microscope should be carried by the arm with the other hand under the base.

http://www.google.com/search?q=microscope+carry&tbm=isch&tbo=u&source=univ&sa=X&ei=-wM2UpGTNI61qAHBs4H4DA&ved=0CEAQsAQ&biw=711&bih=453&dpr=1

So, what is the best answer in the given options?

Your answer -- the arm -- is the only choice that's even partly right.

yes the arm is the correct answer

Yes, the correct answer is d. the arm. The arm is the part of the microscope that is used to carry it. It is typically a curved handle located on the top of the microscope. When picking up or moving a microscope, you should always use the arm to ensure that you have a firm grip and prevent any damage to the delicate parts of the microscope.

A and B