Consider the following statements and choose the correct answer:
1. Every species of animal and plant tends to produce more offspring than can survive within the normal range of the organism
2. There is a strong population pressure tending to force the individuals of each species to spread out and become established in new territories
3. The spread of a species is prevented by highways, such as land connections between continents
4. The spread of species is facilitated by geographical barriers, such as oceans, mountains, deserts and large rivers