Evaluate the Function $f ( x ) = \log _ { 2 } x$

Multiple Choice

Evaluate the function $f ( x ) = \log _ { 2 } x$ at $x = \frac { 1 } { 2 }$ without using a calculator.

A) $0$
B) $- 1$
C) $- 2$
D) $2$
E) $\frac { 1 } { 2 }$