When a polygon, including a pentagon, is dilated by a scale factor \( k \), the lengths of its sides are multiplied by \( k \). In the case when \( k < 1 \), the lengths of the sides decrease.
The area of the polygon is affected by the square of the scale factor. Specifically, the area \( A \) of the polygon after dilation is given by:
\[ A' = k^2 A \]
where \( A \) is the original area and \( A' \) is the new area after dilation. Since \( k < 1 \), \( k^2 \) is also less than 1, leading the area to decrease as well.
Furthermore, the rate of decrease in area is more significant than the rate of decrease in the side lengths because area is proportional to the square of the side lengths.
Therefore, the correct answer to how dilation affects the area of a pentagon when the sides are dilated by a scale factor less than 1 is:
The area decreases more rapidly than the lengths of the sides decrease.