Use process of elimination. From what you gave me to read, you can cross off competition. A drought killed the plants and not competition to live. Go down the list of words and look up the definition. Look at nudation and ecesis later because they are different words that may or may not be challenging to understand. You know what reaction and migration is without looking it up. Once you cross off all words answers that don't match up, ask yourself, which remaining answer goes? Nudation is basically new plants that have successfully started growing after a huge environmental change. Ecesis is sort of similar however, the establishment in a new habitat or environment is not from a big change. Therefore, nudation is the correct answer.
Answer:
The answer is B. It is an endothermic reaction.
Explanation:
Photosynthesis in an endothermic reaction. Endothermic reactions are all those chemical reactions that in their transformation process, in 2 or more different substances, consume Caloric Energy, in which, the products obtained possess higher energy levels, than the initial reagents, since they have taken part of the heat of the environment.