Twenty years ago the Republic of Rosinia produced nearly 100 million tons of potatoes, but last year the harvest bare...

Emil-Kunkin on August 18 at 11:56PM

The author notes there has been decline in yields, and then decides that this decline is a result of researchers' who are concerned only with their own research rather than the needs of the country. This is a pretty weak argument, there are any number of possible causes, and the author decides to focus in on one in particular.

However, C is correct for a different reason. C gives us reason to suspect that by focusing on their own research, the researchers are actually contributing to work that is likely to inadvertently be beneficial.