In the following question, a sentence/part of the sentence is underlined. Below are given alternatives to the underlined sentence/part of the sentence at (a), (b) and (c) which may improve the sentence. Choose the correct alternative. In case no improvement is needed, your answer is (d).
A little rail-road engine was employed by a station yard for doing small pieces of work.
was made by a station yard
was used at the station yard
was employed at the station yard
No improvement
B.
was used at the station yard