Generally, will natural selection result in an increase or decrease in variation? Why does this happen, and how, in theory, will it affect evolution in the future?

how does natural selection lead to evolutions?

Which of the following is true about natural selection? a) It always results in the evolution of new traits b) It always results in the strongest individuals surviving c) It always results in the fittest individuals reproducing d) It always results in the best-adapted individuals surviving

Without mutation, evolution would proceed at a slower pace because changes in allele frequencies would no longer occur. True