According to Euclid's Postulates, through two distinct points there can be only one line that can be drawn.
Therefore, the given assertion is true.
Also, we know that there can be infinite numbers of lines that can be drawn through a single point.
So, the reason statement is also true, but it does not explain why through two distinct points there can be only a single line that can be drawn.
So, assertion (A) and reason (R) are true, and reason (R) is not the correct explanation of assertion (A).