An acre of land has an area of exactly 43,560 square feet. Which of the following is a reasonable estimate for the area of an acre of land?

A. 4 × 10^-4 sq ft
B. 4 × 10^3 sq ft
C. 4 × 10^4 sq ft
D. 4 × 10^-3 sq ft

C. 4 × 10^4 sq ft

This estimate is reasonable because it is closest to the actual area of an acre of land, which is 43,560 square feet.