Set up but do not evaluate the integral that defines the arc length of $e^z=cos(y)$ in the interval $0y\frac{}{3}.$

A$.{\displaystyle \underset{0}{\overset{\frac{}{3}}{}}}\sqrt[\phantom{2}]{(\frac{1}{cos(y)}{)}^{2}1}dy$

B$.$

C$.{\displaystyle \underset{0}{\overset{\frac{}{3}}{}}}sec(y)dy$

D$.{\displaystyle \underset{0}{\overset{\frac{x}{3}}{}}}\sqrt[\phantom{2}]{1-(\frac{1}{cos(y)}{)}^2}dy$

E$.$ None of these.