d ansewr is B .....

this is an xpression thus b^2-4ac <0

thus u get ...........

(2*(4k-1))^2 - 4(15k^2-2k-7)<0

thus u get .........k^2-6k+8<0

solvin u get (k-2)*(k-4)<0

thus 2<k<4

thus k=3.............

hope it helps..................