First of all , the word several at the beginning: it means multiple . This multiple could be happened at the same time or very close each other or maybe not

However, the event kicked off during the weekend. That means that they were very close when they happened on the time line: ranging the weekend from 24 to 48 hours

Therefore the only things that took place and gave concerns among the participants were something that materialized at the same moment or related or concatenated among them in a short amount of time

So, A and D are the correct answers

Coeval and contemporary both have the primary meaning that means happening at the same time as something else,
whereas coincident also means happening at the same time
how do you choose which two are right?