Due to the need to have completely controlled experiments to test a hypothesis, science can not prove everything. For example, the scientific method cannot alone say that global warming is bad or harmful to the world, as it can only study the objective causes and consequences.
Increases. With more food available for the secondary consumers, theres less competition for food. This means the secondary consumers can breed successfully with high chance of offspring survival
The sun is a vital part of the earth, so if it changes energy levels, it will clearly have an affect on the earth. If the energy increases, it'll most likely dry out the grass and melt the snow, etc. If it decreases, the snow could freeze and change the climate.
The answer is surely D cuz I've done this question in a test before. Hoped I helped ;)
