Suppose sin u = x and u is between 0 and pi/2. what is sec u? ... ?

The question should be accompanied with choices, below are the choices:

a) sqrt (1-x^2)

b) x/sqrt (1-x^2)

c) sqrt (1-x^2) / x

D) 1/sqrt (1-x^2)

The answer should be c) sqrt (1-x^2) / x.

cos u = sqrt (1 - sin^2 u) = sqrt (1 - x^2), and cot u = cos u / sin u.