In the question below, the sentence has been given in Active/Passive voice. From the given alternatives, choose the one which best expresses the given sentence in Passive/Active voice.
They have built a perfect dam across the river.
Across the river a perfect dam was built.
A perfect dam has been built by them across the river.
A perfect dam should have been built by them.
Across the river was a perfect dam.
Correct answer is B
No explanation has been provided for this answer.