What is an equation for the translation of (x-2)^2+(y+1)^2=16 by 4 units left and 6 units up?

a. (x+2)^2+(y-5)^2=16

b.(x-2)^2+(y-5)^2=16

c.(x+5)^2+(y-2)^2=16

d.(x+4)^2+(y-5)^2=16