Function that has the same domain as y=2√x

The rest of the question;
A.y=
B.y=
C.y=
D.y=
====================================================

We are given the function
y = 2 √x

The domain for the given function is this
{ x | x ≥ 0 }

The answer is A. y = √2x

In general any function that has a domain of x that is equal to or greater than 0. Some examples:
f(x) = √x  -  2
f(x) = 5 √x