شرکت در آزمون آنلاین زبان انگلیسی 1 - زبان انگلیسی 1 | آزمون شماره 12230

My friends weren't worried at all , so they enjoyed ................................. when they were in Rio.

The law of nature is so odd. The animals that now live on Earth are the results of evolution (evolution: growth and development of something). Darwin was not the first person who believed in the theory of evolution, but he explained it much better than the old-time researchers. This theory says that, when an animal learns a new ability (which is involuntary) that is useful for its survival (survive: continue to live), the animal will live longer and will have a better life than other animals. “It” will pass this ability to its children and its children will have a great chance of surviving and they will pass it to their children and so on.

Because these days people go hunting for food or even for fun in the forests or seas, the evolution cycle of endangered animals is weakened but other creatures like bacteria still grow and will make us sick by new ways. This theory is in question and researchers are still working on it to tell that it is completely true or not.

What is the best title for the passage?

Which sentence is grammatically wrong?