According to one nutrition consultant healthy adults should not hesit

According to one nutrition consultant, healthy adults should not hesitate to consume eggs,
since this food contains
six grams of high-quality protein,
all nine essential amino acids,
vitamins
B12
and D,
and is a source of various other nutrients as well.

six grams of high-quality protein, all nine essential amino acids, vitamins B12 and D are part of a list which doesn't contain an and.
vitamins B12 and D is another list
The food contains [....] and (the food) is [...] - This is another parallelism identifier.

A) vitamins B12 and D, and is a source of various other nutrients - Wrong as identified
B) vitamins B12 and D, and including various other nutrients - Parallelism is broken when including is used
C) vitamins B12 and D, and various other nutrients are included - Same as (A)
D) and vitamins B12 and D, and it is a source of various other nutrients - Seems fine
E) the vitamins B12 and D, and provides various other nutrients - The food contains [...] and (the food) provides [...] is correct but the first list is not segregated using an and

So (D) should be the answer

I also chose D.

Meaning: Healthy adults should not hesitate to consume eggs. Why? Since: 1. this food (an egg) contains: a) six grams of high-quality protein, b) all nine essential amino acids, and c) vitamins B12 and D, and 2. it (an egg) is a source of various other nutrients as well. Two reasons are provided by a nutrition consultant as the reasons why healthy adults should not hesitate to consume eggs and these two reasons are set off by the subordinator since, i.e. since X and Y. X and Y, which are clauses, must be parallel. Secondly, the first clause, X, contains a list of three items. These three must also be expressed in parallel.

and is missing from the list of three items in the first clause. We need and between all nine amino acids and vitamins. In addition, the second clause is missing its subject, it, with it referring to this food (an egg). Eliminate A for these errors.

Like A, B omits and from the three items in list in the first clause. Secondly, including various other nutrients, a participial phrase is not parallel to a clause. A clause with the pronoun it referring to an egg is required. Eliminate B.

Like A and B, C omits and from the three items in list in the first clause. In addition, the second clause shifts from active to passive voice, focusing attention to the contents of an egg without. This is not optimum. In other to maintain parallelism, the active voice is required with the subject of the sentence referring to an egg or this egg, the subject of the previous clause. Eliminate C.

Everything is as expected. The items in the list in the first clause set off by since are expressed in a parallel structure. In addition, the second clause begins with it, which refers to this food or an egg. Everything is fine. Keep D.

The errors in A are mimicked in E. the only difference between A and E is the definite article that modifies vitamins. Eliminate E. I'm not sure if the definite article makes any difference, but maybe Sir generis can elaborate on this in the OE.

D is left as the best answer.

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