Answer:
A.True
Explanation:
Multiple of 3 is given by
3,6,9,12,15,18,,,,
Let one number a=6
6 is a multiple of 3.
Another number =5
5 is not a multiple of 3.
Sum of 6 and 5=6+5=11
We know that
11 is not a multiple of 3.
Therefore, if one number is a multiple of 3 and the other is not , then the sum of these number is not a multiple of 3 is true.
Option A is true