A student is answering a paper in which he can choose 4 question out of 6 to answer. If the paper is divided into 2 sections, A , and B, each with 3 question. The candidate must choose two question form each section, how many ways can this be done?

my working is 3C2 X 3C2= 36 which means i choose 2 out of 3 question from A, and at the same time, i also 2 out of 3 question from B

why cant i do in this way? the ans given is 9 .