I have come across the question: the-idea-behind-the-personal-long-letter-campaign-is-that-a-98990.html
In this topic, people were divided regarding the usage of the verb 'cause' or 'causes'. The OA is A which emphasized the verb should be related to singular noun and many people were in support of D which said the verb should be related to plural noun.
So, I thought of writing this post based on my reading of the article http://grammar.ccc.commnet.edu/grammar/plurals.htm
As per this article, collective nouns, when discussed as a group, are treated as singular otherwise as plural. Examples:
1.A) we're talking about eggs: "A dozen is probably not enough."
1.B) But if we're talking partying with our friends: "A dozen are coming over this afternoon."
2.A) The jury delivers its verdict.
2.B) The jury came in and took their seats.
3.A) The Tokyo String Quartet is one of the best string ensembles in the world
3.B) The Beatles were some of the most famous singers in history.
Note: Generally, band names and musical groups take singular or plural verbs depending on the form of their names:
4.A) "The Mamas and the Papas were one of the best groups of the 70s"
4.B) "Metallica is my favorite band."
Hope this is helpful.