All of the following sentences are compound except

a) people boil or steam rice, and the water is absorbed during cooking.
b) some people prefer their rice with soy sauce, but others like it better plain.
c) rice is the most widely-consumed staple food, especially in asia and the west indies.
d) rice is normally grown as an annual plant; however, it can survive as a perennial in tropical areas.
explain how to identify a compound sentence as well.

All of the following sentences are compound EXCEPT:

C. Rice is the most widely-consumed staple food, especially in Asia and the West Indies.

A compound sentence has at least two independent clauses that have related ideas. The independent clauses can be joined by a coordinating conjunction (for, and, nor, but, or, yet, so) or by a semicolon, as you can see in the compound sentence examples below.

In either case, each half of the sentence must be able to stand on its own as a complete sentence. That means each half needs a subject and a verb. Checking if the different 'parts' of a sentence can be considered by themselves as a complete, autonomous sentence is the way to identify a compound sentence.

In this particular sentence, you only have one independent clause (only one complete sentence): "Rice is the most widely-consumed staple food". The remaining part of the sentence, "especially in Asia and the West Indies", is not a complete sentence as it doesn´t have a subject nor a verb; it depends on the "Rice is the most widely-consumed staple food".

faulty parallelism is a grammar construction where there is no balance in the parts of a sentence they have a similar meaning but the grammar structure is not equivalent.

the correct version of this faulty parallelism in the sentence is:

jefferson wrote the declaration of independence, and he was the nation's third president.

the problem with the first version is that the sentence:

"jefferson was both the writer of the declaration of independence"

presents jefferson as both a subject and an agent for the verb "write" because if he was "the writer" then the declaration of independence was written by him, besides that fact, the sentence presents a dependent clause.

while the second sentence:

he was the nation's third president.

presents a basic subject+verb+object structure

so, to give a proper balance to the structure, or better said, to give a parallel structure, we must write a basic s+v+o structure in both sentences:

jefferson wrote the declaration of independence, and he was the nation third president.