This question has Statement-1 and Statement-2. Of the four choices given after the Statements, choose the one that best describes the two Statements.
Statement 1: Very large size telescopes are reflecting telescopes instead of refracting telescopes.
Statement 2: It is easier to provide mechanical support to large size mirrors than large size lenses.

Let us understand both statements step by step.

First, consider Statement-1: "Very large size telescopes are reflecting telescopes instead of refracting telescopes." A refracting telescope uses lenses to bend (refract) light and form an image, while a reflecting telescope uses mirrors to reflect light and form an image. For very large telescopes, reflecting telescopes are indeed preferred. This is because large lenses in refracting telescopes are heavy and can suffer from issues like chromatic aberration (where different colors of light focus at different points) and sagging due to their weight. In contrast, reflecting telescopes with large mirrors avoid chromatic aberration and are more practical for large sizes. Therefore, Statement-1 is true.

Now, Statement-2: "It is easier to provide mechanical support to large size mirrors than large size lenses." Large lenses can only be supported at their edges because the entire surface must remain unobstructed for light to pass through. This edge support makes large lenses prone to sagging under their own weight, which distorts the image. On the other hand, mirrors in reflecting telescopes can be supported from the back and even from multiple points without blocking the light path, as the light reflects off the front surface. This back support provides better stability and reduces deformation. Hence, it is indeed easier to support large mirrors mechanically compared to large lenses. Therefore, Statement-2 is also true.

Now, we must determine if Statement-2 correctly explains Statement-1. The primary reason very large telescopes are reflectors is because of the mechanical advantage: mirrors are easier to support without deformation. Other factors like avoiding chromatic aberration also play a role, but the mechanical support issue is a key and direct explanation for why reflectors are chosen for large sizes. Thus, Statement-2 provides the correct explanation for Statement-1.

Evaluating the options:

A. Statement-1 true and Statement-2 false → Incorrect, as both are true.

B. Statement-1 false and Statement-2 true → Incorrect, as Statement-1 is true.

C. Both true and Statement-2 is correct explanation → Correct.

D. Both true but Statement-2 is not correct explanation → Incorrect, as Statement-2 is the correct explanation.

Hence, the correct answer is Option C.