Strong communication and long term interaction are normal in this type of group.

Strong communication and long-term interaction indeed are normal in this type of group (). Considering it is a social network aimed at helping students like yourself, the people who answer strive and give their best to answer it properly - both involve strong communication and long-term interaction. 

I’m going to guess these are the choices: a) recreational skiing developed in the mid-19th century b) it was originally invented as a way of getting from place to place in snowy regions c) downhill skiing is currently the only common form of the sport d) it mostly evolved from snowshoeing- if that’s the cases then the answer would be c) downhill skiing is currently the only common form of the sport