Answer:
Correct answer: 
 C) 3x and 8x 
 Step-by-step explanation: 
 At first I thought the correct answer was D. 
 You may have thought that too, but that is not the correct answer. 
 You see 3x and 8x are both like terms because they both have x 
 but 
 the other 3 does not have an x it has y
Explanation:
The like terms would be 3x and 8x