The defect in an engine is detected by using X-rays. The gamma radiation can also be used for the same purpose because gamma radiation has:
(A) Higher frequency than X-ray
(B) Same frequency as that of X-ray
(C) Higher wavelength than X-ray
(D) Same wavelength as that of X-ray

Hint
The gamma radiation can also be used to detect the defect in an engine like X-rays as the gamma radiation is having the frequency higher than X-rays which makes it possible for gamma rays to penetrate the engine just like X-rays.

Complete step by step answer
First, we will understand how a defect in an engine is detected by using X-rays: -
X-rays are high frequency waves in the electromagnetic spectrum. Higher the frequency of the wave, higher will be its penetrating power. X-rays when projected through an engine onto a screen, it gives an image of engine components just like an X-ray conducted for a human body. It is because X-rays penetrate the engine components and reach the screen to form its image. So, if there is any defect in the engine, it can be seen on the screen.
Now, we will understand why gamma rays can also be used for the same purpose: -
Gamma rays have a frequency even higher than that of the X-rays which gives them even more penetrating power than X-rays. So, they can also penetrate the engine and form its image on the screen for the defect to be observed. Thus, they can also be used to detect a defect in the engine.
$ \Rightarrow $ Thus, option (A) is the correct solution.

Note
Although it is important to understand the above concept, an alternate approach to attempt this question is given below: -
Gamma rays have higher frequency and lower wavelength than X-rays. So, option (b), (c) and (d) are ruled out. The only option left is option (a).