A box contains 10 tablets of medicine A and 10 tablets of medicine B. What is the least number of tablets that should be taken from the box to ensure that at least two tablets of each kind are among the extracted.  Choose the correct choice from the following choices
A) 12
B) 15
C) 17
D) 19
E) 21

Rationale: "the worst case scenario will be if we remove all 15 tablets of medicine b first . the next 2 tablets we remove have to be of medicine a , so to guarantee that at least two tablets of each kind will be taken we should remove minimum of 10 + 2 = 12 tablets . answer : a ."
Answer: A