A brother and sister leave home for school. The brother goes 0.5 km East, then turns right and goes 3.5 km and reaches his school. The sister goes 2.5 km North, then 1 km West, then turns left and goes 6 km and reaches her school. Where is the brother's school with respect to the sister's school?

Options

A. 3 km South
B. 7 km South
C. 7 km South
D. 3 Km North