Grids are formed using 1\times1 squares. The grid shown to the right contains squares of sizes 1\times1,2\times2,3\times3, and 4\times4, for a total of exactly 30 squares. Which of the following grids contains exactly 24 squares?

**Answer Choices**

A. <img>

B. <img>

C. <img>

D. <img>

E. <img>