Simplify 3 square root of 10 end root plus 7 square root of 15 end root minus 6 square root of 10 end root minus 4 square root of 15 .
A. 3 square root of 10 end root minus 3 square root of 15
B. 3 square root of 15 end root minus 3 square root of 10
C. 3 square root of 30 end root minus 3 square root of 20
D. 3 square root of 20 end root minus 3 square root of 30
