what is the derivative of y=ln (1-x^2)^1/2

so its hard for me to write all of my work on here but i got 1/2(1-x^2) as my answer and that is one of the choices but it is not the correct choice. the correct answer is -x/(1-x^2) how did they get this answer?

first of all use the rules of logs

y = ln (1 - x^2)^(1/2
= (1/2) ln (1 - x^2)

now ...
dy/dx = (1/2) (-2x)/(1-x^2)
= -x/(1-x^2)