According to the statement, the pine forest grew and gradually replaced the grasses and small plants in an area. This event is likely a secondary succession wherein the old community is slowly restored. Prior to a secondary succession is a natural disturbance, such as wildfires. Oftentimes, the fire also triggers the seeds inside the cones of some pine tree species to germinate. Eventually, under the right conditions, they will grow after several years. Therefore, A is the best answer.

A. I only

Genetic diversity refers to the genetic variation that is present among species. In this case, if there is a wide variety of wild potatoes, it would increase the genetic diversity of the potato crop. Moreover, some species of potato plants would carry useful genes like resistance to pests and diseases. If these useful genes are transferred to the crop plants using some breeding methods, it can increase the value of crop plants.

D. Transfer useful genes from wild potato plants to the crop plants.

The ecological succession which takes place in a barren area that has no existing community due to volcanic explosions and retreating glaciers is called primary succession. Secondary succession refers to the process of taking over a land wherein the residue from the previous ecosystem is still seen. It usually occurs after a natural disturbance, such as floods and wildfire, wherein a healthy ecosystem is devastated when living organisms are wiped out and their shelters are damaged. Therefore, C is the correct answer.

C. A volcanic eruption covers a mountainside with molten rock

Based on the data on the table, the initial number of species in the pond when there is no housing development is 100. When the use of fertilizer is banned, the number of remaining species in the pond is 75, wheres if there is no ban, the remaining number of species is 50.

Therefore, if the use of fertilizer is banned, it would cause the number of species to decrease by 25% after 25 years. This percentage is better than the decrease of 50% when the fertilizer is not banned.

B. Compared to initial conditions, banning lawn fertilizer decreases species diversity by 25 percent after 25 years.