The correct answer is: Â
              →   [A]:  " 3/3,  7/7 "  ;
→  since each ratio in this pair is equal to each other;  that is:
  " 3/3 = 7/7 " ; Â
→  Note:  " 3/3 = (3÷3) / (3÷3) = 1 / 1 = 1 " ; Â
     or:  " 3/3 = 3 ÷ 3 = 1 " ;
 →  And: " 7/7 = (7÷7) / (7÷7) = 1 / 1 = 1 " ; Â
     or:  " 7/7 = 7 ÷ 7 = 1 " ;
Thus: Â " 3/3 = 7/7 = 1/1 = 1 " .
Let us consider the other answer choices:
Choice [B]:  " 1/3, 3/5 " ;  is incorrect;  since:  " (1/3) ≠(3/5)" .
 Note:  "(1/3) = 0.3333 )"  ;  and:  "(3/5) = 0.6 " .
  0.3333...  ≠ 0.6 .
Choice [C]:  " 4/3, 3/4 ", is incorrect; since:  " (4/3) ≠(3/4) " .
 Note:  "(4/3) = 1.33333 ...) " ;  and:  "(3/4) = 0.75 ".
  1.3333 ≠0.75 .
Choice [D]: Â " 6/1000, Â 12/1000 " ; Â is incorrect ;
  since:  "6/1000 ≠12/1000 " ;  And:
  since:  "6" out of 1000" is less than:  "12" out of "1000" ;
  → Specifically:  0.006 ≠ 0.012 .    Â