Answer: Disease (economic disruptions) Also keep in mind that bacterica, cancer, tumors etc. were not brought up till the 1980's - 2000's
Explanation: Look at my comment because it got cencored for some reason
D! all of the others are commonly used
There are C. primary gases
The climate 250 mya was very tropical, so maybe those fossils could've been found there even w/o continental drift