If `tantheta=sqrt(a/b)`where `a , b ` are positive reals then the value of `sinthetasec^7theta+costheta cosec^7theta` is- a.`((a+b)^3(a^4+b^4))/((a b)^(7//2))` b. `((a+b)^3(a^4-b^4))/((a b)^(7//2))` c.`((a+b)^3(b^4-a^4))/((a b)^(7//2))` d. `((a+b)^3(a^4+b^4))/((a b)^(7//2))`