The diffraction limit is a limit on: The diffraction limit is a limit on: A telescope's size. A telescope's angular resolution. A telescope's spectral resolution.

A telescope's angular resolution.

Explanation:

Diffraction limit is a minimum angular separation of two sources and it can be distinguished by the telescope. This angle is known as the diffraction limit. It is proportional to the wavelength of light and it has an inverse relation with the diameter of the telescope. Mathematically  it is defined as

θ = 1.22λ/d

where θ is the angle, λ wavelength and d is the diameter of the objective mirror (lenz).

answer: a. same unit

explanation:

conduction, convection, radiation