1 – Correct
Competition between individuals of the same species is known as intra-specific competition. Intra-specific competition is a part of natural selection.
2 – Correct
Competition between individuals of different species is known as inter-specific competition. Inter-specific competition is a part of natural selection.
3 – Correct
Natural selection can lead to evolution when individuals with certain characteristics have a greater chance of survival as compared to individuals who do not have those characteristics. When such individuals reproduce, they pass their advantageous characteristics on to their offsprings.
4 – Correct
Natural selection can lead to extinction when individuals do not have certain advantageous characteristics. This causes them to have a lesser chance of survival, eventually leading to extinction.