The mongol empire covered vast lands; the mongols themselves were known as
multiple generations of military people.
nomadic herdsmen with with excellent equestrian skills.
fierce and ruthless warriors.
explorers seeking additional agricultural land.

According to the statement "The Mongol Empire covered vast lands; the Mongols themselves were known as" and the set of options, the answer is C.

A. multiple generations of military people.

B. nomadic herdsmen with excellent equestrian skills.

C. fierce and ruthless warriors.

D. explorers seeking additional agricultural land.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.

this is a good question! i'll do some research and come back when i have the answer!