The correct answer is:
___________________________________________________
[A]: "index fingers". Note that you want to keep your left index fingers near the "ASDF" keys; and your right index fingers near your "JKL;" keys; so you use your "index fingers" for easier dexterity to "reach" for the other keys to more easily "access", or "reach", the "reach keys" ; and then retract those fingers to the original positions.
____________________________________
