A natural ingredient in many foods, small amounts of sodium are as ess

The clause "a natural ingredient in many foods" refers better to "sodium" than to "small amounts of sodium."

As the "ingredient" is "sodium," and the amount is irrelevant, "sodium" should immediately follow the clause "a natural ingredient in many foods."


A natural ingredient in many foods, small amounts of sodium are as essential to the body as air and water are.

(A) A natural ingredient in many foods, small amounts of sodium are as essential to the body as air and water are
"A natural ingredient in many foods" should modify "sodium."

(B) As a natural ingredient in many foods, small amounts of sodium are as essential to the body as air and water
"A natural ingredient in many foods" should modify "sodium."

(C) As a natural ingredient in many foods, in small amounts, sodium is as essential to the body in small amounts as is air and water
"A natural ingredient in many foods" should modify "sodium". The phrase "in small amounts" would be more ideal following "sodium." Also, this answer introduces a subject/verb agreement error.

(D) A natural ingredient in many foods, in small amounts, sodium is as essential to the body as is air and water
"A natural ingredient in many foods" should modify "sodium." The phrase "in small amounts" would be more ideal following "sodium." Also, this answer introduces a subject/verb agreement error.

(E) A natural ingredient in many foods, sodium, in small amounts, is as essential to the body as air and water are.[/quote]
The clause "a natural ingredient in many foods" now directly refers to sodium.

This makes C the most likely answer.

I think the best version of the sentence would change the order from "as air and water are" to "as are air and water," but this shouldn't change the answer to the question.