Read this sentence.

genetic modification makes pest-resistant corn, but genetically modified corn may be unhealthy.

what type of sentence is this?

a.
compound-complex

b.
complex

c.
simple

d.
compound

The sentence above is a compound sentence.

Explanation:

A compound sentence joins two or more independent clauses with a coordinator such as and, but, for, or a semi-colon. Independent clauses are two phrases that can stand alone as a sentence because they represent a complete thought. They do not depend upon one another, but tie together similar ideas.

In the sentence above, the independent clauses have been joined by the coordinator but.

1) Genetic modification makes pest-resistant corn (independent clause I)

2) But genetically modified corn may be unhealthy. (independent clause II)

adverb is the answer i believe.