AMC 12B 2016 Problem 1

[system]

What is the value of

\dfrac{2 a^{-1}+\dfrac{a^{-1}}{2}}{a}

when a=\dfrac{1}{2} ?

Answer Choices
A. 1
B. 2
C. \dfrac{5}{2}
D. 10
E. 20