3. Let U (universal set) = {p, r, o, b, l, e, m, a, t, i, c}, R= {r, a, t, i, o}, and T = {t, a, b, l, e}. Let S = TUR. Set S contains how many distinct elements? (A) 2 (B) 3 (C) 7 (D) 8 (E) 10 ​