The next term of the A.P., 7 , 28 , 63 , . . . . . .

Answer: Option D

$$\begin{array}{rl}& \text{A}\text{.P}\text{.}\text{is}\sqrt{7},\sqrt{28},\sqrt{63},......\\ & \Rightarrow \sqrt{7},\sqrt{4\times 7},\sqrt{9\times 7},.....\\ & \Rightarrow \sqrt{7},2\sqrt{7},3\sqrt{7},......\\ & \therefore Herea=\sqrt{7}\text{and}\\ & d=2\sqrt{7}-\sqrt{7}=\sqrt{7}\\ & \therefore \text{Next}\text{term}=4\sqrt{7}\\ & =\sqrt{\left(16\times 7\right)}\\ & =\sqrt{112}\end{array}$$