First, let's take note of the room's current area. Recall that the area of a rectangle is equal to the product of its width and length. Given a 20 ft by 35 ft room, we can compute for its area as shown below.
A = W(L) = (20 ft)(35 ft) = 700 ft²
Now, since the length will be increased by 10 ft, its new dimension would be equal to (35 + 10) = 45. Thus, the new area would be
A = W(L) = (20 ft)(45 ft) = 900 ft²
Comparing the two areas, we can see that the area would increase by (900 - 700) = 200 ft².
Answer: A. The area increases by 200 square feet
