Which option is an example of a simple sentence?
a. processed foods are very high in saturated fats and have very little nutritional value.
b. processed foods should be avoided because they can lead to serious health problems.
c. processed foods are a staple of the american diet.
d. processed foods are usually less expensive to purchase and easier to make.

The correct answer is C. Processed foods are a staple of the American diet.

Explanation:

In general terms, there are three types of sentences: simple, complex and compound. A simple sentence is a sentence composed only by one clause usually containing a subject, a verb and a complement which expresses a complete idea or thought (independent clause). On the other hand, compound sentences contain one independent clause (phrase that expresses a complete idea) and one dependent clause (phrase that does not express a complete idea) joined by words such as after, while or since  and compound sentences are composed of two independent clauses joined by conjunctions such as and or punctuation sign such as comma or semicolon. In the case of "processed foods are a staple of the American diet" this is a simple sentence as it is compound only by one subject (processed foods), one verb (are) and one complement (a staple of the American diet) and in general only one clause or complete idea.

the correct answer is: d