Answer:
Because they believed that there were few significant scientific achievements.
Step-by-step explanation:
The Dark Ages was a period between the decline or fall of the Roman empire during the 5th century to the Renaissance in the 14th century. This period in between the two eras also came to be synonymous with the Middle Ages.
The period was called "the Dark Ages" because of the lesser development in the field of economy, social, cultural, or even science and the arts, like painting and literature. This period saw little to no achievements compared to the times before and after it.
Thus, the correct answer is the second option.