Select the option that will come next in the following series.

mc, hx, cs, xn, si, ?

​Given: mc, hx, cs, xn, si, ?

Logic: 1^st and 2^ndletters are decreasing by 5 places.

The first letters are: m, h, c, x, s
m (13), h (8), c (3), x (24), s (19)

m – 5 = h, h – 5 = c, c – 5 =x, x – 5 = s, s – 5 → n

The second letters are: c, x, s, n, i
c (3), x (24), s (19), n (14), i (9)

c – 5 =x, x – 5 = s, s – 5= n, n – 5 = i, i-5 4 → d

The next term is: nd

thus, correct option is (b).