c. succession…relevant
It's not A since "a observation" doesn't make sense. Also, it's not b or d because these words have a positive connotation. The sentence should include words that are negative since it's talking about why there are more hungry people in the world today. E is also wrong because pyramid doesn't make sense and you also usually say "characteristic of" not "characteristic to". Option C is the only option left. It would make sense because succession means a series of economic crises. Relevant can also work well in the second blank.