1. which is an open-ended question that could be used to start a discussion?
do you take the bus?
why do you think the bus should run more often?
what time does the last bus leave?
how many people take the bus?

An open-ended question is that could be used to start a discussion, 'Why do you think the bus should run more often?' is an open-ended question.

B

Explanation

A question which does not have an answer as 'yes' or 'no' are open-ended questions.

They are questions where the answers are expected to be more than a single word.

To start a group-discussion or conversation, these questions play a vital role in bringing opinions of everyone participating in the discussion or conversation.

The rest questions mentioned above have answers only as 'yes' or 'no'.

some sort of sound device i believe.