To identify the correct answer, we need to understand the meaning and structure of the given sentence. The sentence states that James Watt discovered the energy of steam. We need to rewrite this sentence in passive voice, where the subject (James Watt) becomes the object, and the object (the energy of steam) becomes the subject.
Let's analyze the given options:
A:
The energy of steam discovered James Watt.
This option changes the meaning of the sentence by stating that the energy of steam discovered James Watt. This is incorrect because it was James Watt who made the discovery, not the other way around.
B:
The energy of steam was discovered by James Watt.
This option correctly rephrases the sentence in passive voice, with the subject (the energy of steam) being discovered by James Watt. This is the correct answer.
C:
James Watt was discovered by the energy of steam.
This option changes the meaning of the sentence by stating that James Watt was discovered by the energy of steam. This is incorrect because James Watt was not discovered by steam, but rather he made the discovery.
D:
James Watt had discovered energy by the steam.
This option is grammatically incorrect. The word "by" is missing before "the steam", and the use of "had discovered" is unnecessary.
Therefore, the correct answer is option B:
The energy of steam was discovered by James Watt.