A: - A red object appears dark in the yellow light

R : - A red colour is scattered less

A red object look red because it reflects only red colour and absorbs all other colours present in the white light. Hence, when red object is seen through yellow light then it absorbs yellow colour falling on it and appears dark. Also, from Rayleigh's Criteria of scattering

Scattering $\propto \frac{1}{{\lambda }^4}$

Since, red colour has a larger wavelength it is scattered least.

Hence, both A and R are true but R is not the correct explanation of the A