Multiple choice $[8]$:

A horizontal curve has $M($relative to the vehicle path$)=16ft$ and $\frac{?}{?}($corresponding to the sight distance$)=30$ degrees. The highway has two $12-$ ft lanes per direction. The sight distance, $S,$for this road is closest to:

a$)496$ ft

b$)243$ ft

c$)485$ ft

d$)246$ ft