Final answer:
In the provided sentence, 'evaporation' and 'enhancements' are nouns functioning as direct objects, as they receive the action of the verbs 'investigated' and 'designed,' respectively.
option 'd' is the correct
Step-by-step explanation:
In the sentence 'He investigated evaporation as a cooling technique and designed nautical enhancements, including watertight compartments,' the words 'evaporation' and 'enhancements' serve as nouns in the sentence. Specifically, they are functioning as direct objects.
The subject of the sentence is 'He,' which performs the actions, while the verbs 'investigated' and 'designed' are transitive verbs that require a direct object to complete their meaning.
The nouns 'evaporation' and 'enhancements' are the recipients of the actions from these verbs. Thus, the correct functioning of these nouns in the sentence is Option D) Direct objects.
By receiving the action of the verbs, these nouns serve to manifest what the subject is acting upon within the sentence structure.