We have the following:
The mechanical advantage is obtained by dividing the circumference of the shaft by the pitch of the screw.
[tex]\begin{gathered} c=2\pi r \\ c=2\cdot3.14\cdot2.1=13.19 \end{gathered}[/tex]now, let ma mechanical advantage
[tex]\begin{gathered} ma=\frac{13.19}{1.3} \\ ma=10.1 \end{gathered}[/tex]Therefore, the answer is B. 10.1