Correct Answer: Ashok was at the bus stop.

Solution : The correct option is the fourth option.

The sentence "Ashok was at the bus stop" is correct in terms of its use of the preposition at.

The preposition at is used to indicate a specific location or position. In this case, it specifies where Ashok was located, which is the bus stop. At is appropriate here because it denotes a point or a particular place where Ashok was present.

Therefore, the sentence accurately uses the preposition at to convey Ashok's location, indicating that he was positioned or situated at the bus stop.