The correct option is C (x−3)(x+8)
In order to factorize x2+5x−24,we need to split the middle term 5xsuch that the sum or difference is 5 and product is -24.
Hence 5x can be written as -3x and 8x.
x2−3x+8x−24=x(x−3)+8(x−3)
Taking out (x−3)common,x2+5x−24=(x−3)(x+8).