If a, b, c, and d are four positive increasing integers such that a, b, c are in A.P. and b, c, d are in G.P. and d = 30, find the four numbers.

(a) 5, 10, 20, 30
(b) 3, 6, 12, 30
(c) 2, 4, 8, 30
(d) 1, 2, 4, 30