Answer:
The correct choice for <em>a</em> and <em>b</em> is 2 and 6 respectively.
Step-by-step explanation:

The least common multiple in the provided expression is x+2. Therefore, the above expression can be written as:

Arrange the like terms together as shown:

It is given that after simplified her answer was x+1. Therefore, this information can be written as:

Multiply numerator and denominator by
we get,

Further simplify,

Add the like terms:

Now compare the coefficient of x term and constant term.
a+1=3 and b-4=2
further solve:
a=2 and b=6
Hence, the correct choice for <em>a</em> and <em>b</em> is 2 and 6 respectively.