Simplify the following
$$7\frac{1}{2} \div\left\{4\frac{1}{4}-\frac{1}{2}\times\left(2\frac{1}{2}-1\frac{1}{4}-\frac{3}{4}\right)\right\}$$

A

1.875

B

7.25

C

4.5

D

5.75