Race

Why do liberals call it a social construct?
When they say 'race has no biological basis in reality' do they mean 'race as the social construct implies it is has no biological basis in reality' or just plain denial?

Libs call it a social construct because the goal of the cultural Marxist is to de-construct society to make way for communism. They want things that have been a given since time began (race, gender stc..) to be questioned.