The correct option is C 4x2−y2
Let the expression to be subtracted be A.
⇒(2x2−4y2+6xy+10)−A=−2x2−3y2+6xy+10
⇒A=(2x2−4y2+6xy+10)−(−2x2−3y2+6xy+10)
Grouping the like terms together,
⇒A=(2x2+2x2)+(−4y2+3y2)+(6xy−6xy)+(10−10)
⇒ A=4x2−y2
Hence, the expression that needs to be subracted is 4x2−y2.