Question

For the telescope to have large resolving power the
A. The focal length of its objective should be large
B. The focal length of its eyepiece should be large
C. The focal length of its eyepiece should be small
D. An aperture of its objective should be large

Answer 1

Telescopes are used to see the objects that are placed at a far distance. It produced an image bigger than the real image and it can be seen with the bare eye In most telescopes the images are inverted.

Complete step by step solution:
The resolving power depends on the aperture and it is linear to the aperture. That is when the aperture is doubled or it increases by two. i.e. a Telescope having an aperture of 4 inches and its resolution is about $1$ arc second, a $40$ -inch Telescope can resolve $0.1$ arc seconds.
The splitting of double stars is a real test of resolving power. Epsilon Lyrae is frequently used for a baseline of an amateur scope quality. It is a double-double. If you can see it with your unaided eye you have good dark skies. By the Telescope, the two stars are two doubles separated by $2.3$ arc seconds.
It fully depends on wavelength and objective diameter: the diffraction of light is the limiting factor. For accuracy optical surfaces.
So, option (D) is the correct answer.

Note:
The resolving power mainly depends on the focal length’s diameter
The resolving power did not change even we change the focal length
If the focal length of the object is increased then the magnification also increases.