Answer:
B. Had great value
Step-by-step explanation:
The words that are underlined in sentence 2 are were really cool. This type of language, which we usually use in everyday conversations with our friends, isn't used in informational texts, i.e. texts that give us information about a certain topic. Instead, we should use more formal language. The best substitute would be the words had great value.
Option A is incorrect because it also contains informal language (totally useful - very useful would be better).
Option C also isn't formal enough (had a ton of uses - had many uses is a better version).
Option D is incorrect because the given combination of words isn't correct. Something can't be way important. It can just be very important.
This is why option B is correct.