Answer:
The correct option is A.
Step-by-step explanation:
If the degree and variables of two terms are same, then they are called like terms.
In option A.
The given expression is
Here, 4ab and -3ab are like terms because both have same variables a and b with degree 1.
By combining like terms we get
In options B, C and D, there are no like terms, So only the expression
we can simplify by combining like terms.
Therefore the correct option is A.