Which set of keys is your left ring finger responsible for typing?

a. 1, q, a, and z
b. 2, w, s, and x
c. 3, e, d, and c
d. 4, r, f, and v

The answer is:   [B]:   " 2,  W, S, and X " .

Note:  
          Among the answer choices given, one's "left ring finger" is the finger responsible for the use of these characters— 
 [which are listed in "Answer choice:  [B]:  
 
        "The number '2' ; the letter 'w' ; the letter 's'; and the letter 'x' ."].
 
     This is according to the proper placement of one's fingers using the "QWERTY" (pronounced "quirty") style keyboard—AND method (i.e. proper finger placement); and, back in the OLD days, typewriter—and still is used today (April 2017)—even with the popularity of iPhones and speak recognition systems!  And yes, the term "QWERTY" does come from the sequential letters on the standard "keyboard/typewriter"—"Q,W,E,R,T,Y".

Additional Notes:  

Choice:  A):  "1, Q, A, and Z" ; is INCORRECT ;  this would involve the use of one's "left pinky finger" — NOT one's "left ring finger".

Choice:  C):  "3, E, D, and C" ; is INCORRECT ; this would involve the use of one's "left middle finger" — NOT one's "left ring finger".

Choice:  D):  "4, R, F, and V" ; is INCORRECT ;  this would involve the use of one's "left index finger" — NOT one's "left ring finger".

{Fun fact:  The word: "typewriter" can be spelled using letters only found on                       the "QWERTY" row of the "QWERTY"-style keyboard.}

        →     Hope this {lengthy} answer is helpful!