The Struggle To Survive

When darwin spoke of the struggle for existence and survival of the fittest in the nature he was convinced that

Assertion (A): Natural selection is the phenomenon by which the nature selects those species which possess survival advantage over the other species. Reason (R): According to theory of natural selection, there is struggle of existence within the species of a population for the environmental resources and their struggle leads to survival of certain organisms and elimination of the less competent species. a) Both A and R are true and R is the correct explanation of A. b) Both A and R are true but R is NOT the correct explanation of A. c) A is true but R is false. d) A is false and R is true.

Which one provides correct sequence of events in origin of species according to Darwinism ? 1. Natural selection 2. Variations and their inheritance ? 3. Survival of fittest 4. Struggle for existence

Define struggle for existence.