Answer: When parallel light rays strike a concave lens, they will diverge that is they spread out.
Concave lens is also known as diverging lens, which means that when parallel rays of light strike on it, the lens spreads out the light rays ( that is it diverges the rays of light) that are refracted through it.
It is thinner at center as compared to edges and used to correct myopia ( a defect of vision that is also termed short-sightedness).
Therefore, when parallel light rays strike a concave lens, they will diverge that is they spread out.