Hi Akash,
For the farmer who takes care to keep them cool,
providing them with high-energy feed, and milking them regularly, Holstein cows are producing an average of 2,275 gallons of milk each per year.
Well, this question is certainly confusing and not written in the best possible manner. However let’s get into the logic of this sentence. The sentence is saying that for the farmers who takes care of the Holstein cows in certain ways, these cows produce an average of 2,275 gallons of milk each per year. Now here comes the tricky part. The ways in which the farmers takes care of these cows is that he takes care:
a. to keep them cool,
b. to keep them provided with high-energy feed, and
c. to keep them milked regularly.

1. From the original sentence, it is clear that the entities in the list are not parallel. While “cool” is an adjective, “providing…” and “milking…” are working as gerunds (nouns) in this sentence.
2. In case, if you could not figure out the correct parallel list to rectify it, look at the problem this way. “providing…” and “milking…” are the verb-ing modifiers preceded by comma. This means that they are modifying the preceding clause. However, it does not make sense to say that the farmer keeps the cows cool by providing them good feed and by milking them. So these modifiers do not fit here.
3. Also notice the inconsistent verb tenses. This sentence is providing general information about the Holstein cows. Using present continuous tense “are producing” does not make sense here.
POE:
a. providing them with high-energy feed, and milking them regularly, Holstein cows are producing:
Incorrect for the reasons stated above.
b. providing them with high-energy feed, and milked regularly, the Holstein cow produces:
Incorrect. 1. The verb-ing modifier “providing…” does not make sense as in choice A.
2. The entities in the list are still not parallel.
3. The singular antecedent “the Holstein cow” does not agree in number with plural pronoun “them”.
c. provided with high-energy feed, and milking them regularly, Holstein cows are producing:
Incorrect. 1. Verb-ing modifier “milking…” does not make sense.
2. The entities in the list are still not parallel.
3. Use of “are producing” is incorrect.
d. provided with high-energy feed, and milked regularly, the Holstein cow produces:
Incorrect. The singular antecedent “the Holstein cow” does not agree in number with plural pronoun “them”.
e. provided with high-energy feed, and milked regularly, Holstein cows will produce:
Correct. The use of future “will produce” is correct because we have a causal relationship here. If the farmers take care of the cows in certain ways, then the cows produce certain amount of milk. The cause is written in the simple present. Hence, the effect can be written in either simple present tense or simple future tense.
Hope this helps.
Thanks.
Shraddha
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