To answer is 1/K>0, if we can find is K>0 Option1: K < 0 does not satisfy the condition. Therefore, K has to be >0. Thus sufficient. Option2: a. K >0 satisfies the cond. b. K =-0.5 also satisfies the condition. Therefore, K can be either >0 or <0. Thus, insufficient. Hence, only option "A"...