Hint: The nose piece is additionally referred to as the revolving turret. It holds the target lenses. It is movable, that is why it can revolve the objective lenses depending on the magnification power of the lens.
Nosepiece is the circular structure where the various objective lenses are screwed in. to vary the magnification power, simply rotate the turret. A normal microscope has three or four objective lenses with various magnifications, screwed within a circular "nosepiece" which can be rotated to pick the specified lens. These lenses are frequently color-coded for easier use. Objective turret, revolver, or revolving nosepiece is the portion that carries the set of objective lenses. It allows the user to modify between objective lenses. The objectives are exposed and are mounted on a rotating turret in order that different objectives are often conveniently selected. Standard objectives comprise 4x, 10x, 40x and 100x however different power objectives are present.
High power or light microscope achieves higher levels of magnification than a stereo or low power microscope. It wants to view smaller specimens like cell structures which can't be seen at lower levels of magnification. Essentially, a light microscope consists of structural and optical components. Although, inside those two basic systems, there are few important parts that each microscopist should know and understand. These key microscope parts are illustrated and explained below. Some microscopes use an oil-immersion or water-immersion lens, which may have magnification greater than 100, and a numerical aperture greater than 1. These objectives are specially designed to be used with an index of refraction matching oil or water, which must fill the gap between the front element and therefore the object. These lenses give greater resolution at high magnification. Numerical apertures as high as 1.6 are often achieved with oil immersion.
So, the correct answer is option (d) ‘Both B and C’.
Note: The resolving power of an objective lens is measured by its ability to differentiate two lines or points in an object. The greater the resolving power, the smaller the minimum distance between two lines or points which will still be distinguished. The higher the numerical aperture, the higher will be the resolving power.