Which piece of evidence from the text details what may have caused the riots to occur

Alleged stabbing and beating of a local shop owner.

Explanation:

The Text in question is a Reuters News Agency article titled "A Tense Calm On Brazil-Venezuelan Border After Anti-Immigrant Riot".

It is no secret that Venezuela have been going through some tough Economic times for a couple of years now and this had led to a significant number of it's people trying to leave the country for greener pastures. One of those such placed is Brazil with which they share a border with.

Venezuelans are able to enter through the Pacaraima border post however, on the Friday before this article was published, four alleged Venezuelan immigrants severely beat up a local shop owner in the town of Pacaraima. The local residents were enraged by this and in the riot that ensued, chased 1,200 Venezuelans, including women and children, back into Venezuela and destroyed the tents they were camping in as well as burning the belongings left behind.

the correct answer is the first one.