Identify the missing letters in the series: m, o, q, s, ?

A. U

What letter should replace the question mark in the series: b, d, f, h, ?

A. J

Find the missing letters in the series: a, d, g, j, ?

A. M

Teacher is to Student as Doctor is to ?

A. PATIENT

Bird is to Nest as Fish is to ?

B. TANK