`int_0^1 sqrt(x(1-x)) dx` equals

Mark the correct alternative in each of the following: int_0^1sqrt(x(1-x))dx equals pi//2 (b) pi//4 (c) pi//6 (d) pi//8

int_0^1 x/sqrt(1-x^2)dx

int_0^1 x/sqrt(1+x^2)dx

int_0^1 x/(1+sqrt(x))dx

int_0^1 (x)/(sqrt(1-x))dx=

int_0^1 dx/sqrt(1-x^2)

int_0^1 x/sqrt(1+x)dx

int_(0)^(1)sqrt(x+1) dx =

What is int_0^1 x(1-x)^n dx equal to