Option a:
is the equivalent expression.
Step-by-step explanation:
The expression is
where

Let us simplify the expression, to determine which expression is equivalent from the four options.
Multiplying the powers, we get,

Cancelling the like terms, we have,

This equation can also be written as,

Multiplying the terms in denominator, we have,

Thus, the expression which is equivalent to
is

Hence, Option a is the correct answer.