The correct answer is C. past tense.
Past tense is a grammatical tense used to describe an action or event that is done in the past. "Mixed" has a regular form "mix" and by adding "-ed" to it, it becomes a past tense.
A characteristic of informal writing is slang, abbreviations, short hand, or lack of punctuation.
The supporting sentence that makes use of an example is:
Beto used interval training to prepare for and win a marathon.
In this excerpt, the first sentence is the <em>topic sentence</em>, which is the sentence that contains the main idea. The second sentence is the supporting sentence that gives the reader further information about the topic. In the third sentence, the writer gives a specific example to support the main idea. Finally, in the last sentence, the writer provides factual information to make the topic sentence more relevant.
