One reason the Russian Empire was difficult to unite was that it A) had many diverse ethnic groups B) possessed limited natural resources C) served as a crossroads for trade D) lacked a navy

B. Possessed limited natural resources Although Russia is massive, the majority is Siberia or a barren winter wasteland. It is very difficult to grow crops and mining is almost out of the question. For those reasons Russia was hard to unite because supplies and necessities were hard to come by.

Has very many diverse ethnic groups