14. Tasha is counting votes from a school election. There were 3 candidates running for treasurer, and students either voted for 1 of those 3 or they didn't vote at all. If there are 420 students in the school and half of them voted for Marcus, one- third of them voted for Mary, and one-seventh voted for Edward, how many students did not vote? (A) 10 (B) 20 (C) 42 (D) 105​