AMC 12A 2018 Problem 12

Let S be a set of 6 integers taken from \{1,2, \ldots, 12\} with the property that if a and b are elements of S with a<b, then b is not a multiple of a. What is the least possible value of an element of S ?

Answer Choices
A. 2
B. 3
C. 4
D. 5
E. 7