7. Jerry and Sylvia plan to walk from the southwest corner to the northeast corner of a square plaza. Jerry walks east first and then north to reach the destination, but Sylvia walks straight in the northwest direction. Then Sylvia walks ( ) less than Jerry.
(A) $30 \%$
(B) $40 \%$
(C) $50 \%$
(D) $60 \%$
(E) $70 \%$
7. A.
$$
\frac{2-\sqrt{2}}{2} \times 100\% \approx \frac{2-1.4}{2} \times 100\% = 30\% \text{.}
$$