Which would most likely be found in informal writing? scholarly language complex sentences opinion statements lengthy descriptions

Since informal writing is the act of acting unproperly, or as you do with friends or in text - stating opinions may be quite common. 

It doesn't make sense to use complex sentences, scholarly language, or lengthy descriptions informally. That's meant for more formal occasions, such as teaching a particular subject or discussing with people of high intellectual knowledge in a formal event.

Hope should be your answer.

In is the prepositional phrase