Answer:
C. All values of x make the equation true.
Explanation:
A solution of an equation is a value for which the equation is true,
If after solving an equation no variable term remains,
Then, there can be two cases,
No solution : if after solving, an equation gives a false statement.
Infinitely many solutions : If after solving, the equation gives a true statement.
Here, the given equation,

( By associative property )
Which is a true statement,
Hence, by the above explanations it is clear that all values of x make the equation true.
Option C is correct.