The correct option is D 6a is the factor of both the terms and divides each term completely.
In the expression 36a+6×17a,
first term =36a
second term =6×17a=102a
Dividing 36a with 6a=36a÷6a=6
Dividing 102a with 6a=102a÷6a=17
So, it means that 6a is the factor of expression as it divides both terms.
Hence, option D is correct.