Final answer:
Both primary and secondary succession exhibit a gradual maturation of biological change in an area over time, which makes Option 2 the correct answer to the question of how they are similar.
Step-by-step explanation:
Primary and secondary succession are similar in that they both Show a gradual maturation in biological change of an area over time. Primary succession takes place on new land, such as land formed by lava flows or land left after a glacier retreats, where there were no previous organic materials or soil. It starts from the bare rock, and pioneer species like lichens and some plants help break down the rock into soil, allowing other species to grow in the future. Secondary succession occurs in areas where soil exists but the ecosystem has been disturbed by events such as wildfires, floods, or human activities like agriculture. Here, pioneer species don't need to create soil but instead utilize the remaining nutrient-rich soil to reestablish vegetation gradually.
Option 2 mentioned in the question is the correct answer because it encapsulates the essence of both primary and secondary succession, focusing on the gradual change and development of an ecosystem following a disturbance. Option 1 is only sometimes true, Option 3 is incorrect as autotrophs produce oxygen rather than carbon dioxide, and Option 4 pertains mainly to secondary succession.