Like term as 4m³n² is

⇒ Like term are the terms which have same variable and powers. The coefficients need not to be matched.

⇒ Here 4m³n² and – 6m³n² are like term. Because they have same variables and powers.

Option (a) does not match to our solution.

Option (b) does match to our solution.

Option (c) does not match to our solution.

Option (d) does not match to our solution.

So, option B. is correct answer.