He had solved the doubt. change to passive voice​

Functions of the passive voice. The passive voice is used to show interest in the person or object that experiences an action rather than the person or object that performs the action. In other words, the most important thing or person becomes the subject of the sentence.

Explanation:

third person

explanation:

note the usage of names and pronouns, "james" & "the old man". this alone can confirm it as third person, as first person uses "i" and the like, while second person uses "you" and the like.

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your answer is c) experiments with water vapor showed that elements combine in specific proportions.