The correct option is A 2 4 6
By trying all the given option combinations we find that option (A) i.e., CAT stands for 246 doesn't satisfy the expression ACT AT = 11 as in this case, we will have
ACT = 426 and AT = 46
Now, 426 46 = 9 approx which is not equal to 11.
While all the other options on putting the values will definitely give the result ACT AT = 11.
Hence, option (A) is the correct answer.