Hey there! 
Looks like we have to identify our like terms in this expression 
For A. its a variable x constant & variable (so this can be your answer)For B. its a variable and a constant (not your answer)For C. its both variables (this can be your answer)For D. it is a constant and variableThe only one with a like terms would be 
option C (also your answer)Good luck on your assignment and enjoy your day! 
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