The first seven multiples of 5 are:
\[
5, 10, 15, 20, 25, 30, 35.
\]
The mean is given by:
\[
\text{Mean} = \frac{\text{Sum of terms}}{\text{Number of terms}}.
\]
The sum of the terms is:
\[
5 + 10 + 15 + 20 + 25 + 30 + 35 = 140.
\]
Thus, the mean is:
\[
\frac{140}{7} = 20.
\]
Thus, the correct answer is \( \boxed{20} \).