Who Comes on Day 21?

Difficulty: Hard · Topics: Discrete Mathematics, Sets, Word Problems

Some of the people who registered for a new sports course will come every 2 days, and the others will come every 3 days.

The sets of the people who come to the course on days 1, 2, 3, 4, 5 and 6 are A, B, C, D, E and F respectively, and

Acup B=\e,c,a,d,b,g\

D-B=\a,d\

Ccap E=\c,e\

F=\b,f\

Which of the following is the set of the people who come to the course on day 21?