The volume of the solid bounded by $y^2+z^2=4,x=2y,x=0,$ and $z=0$

in the first octant is

a$.\frac{16}{3}$

b$.\frac{4}{3}$

c$.\frac{8}{3}$

d$.\frac{3}{8}$

e$.\frac{3}{2}$