$10=2\times 5$,  the length is $5$ and the width is $2$.  $(2+5)\times 2=14$. 
The values of length and width of a rectangle are both prime numbers. If the area of that rectangle is $10$, what is its perimeter? 
(a) $$5$$ 
(b) $$7$$ 
(c) $$10$$ 
(d) $$14$$ 