Let's suppose we are in an advanced stage of the recruiting process of a company and this question pops up. I wanted to point out the nuance of being an startup since who is interviewing is not an HR agent but the whole startup team instead (four members), in case it can have any impact (maybe the fact that they are less professional and more emotionally driven on this aspect).
The truth is "yes", but in a more early stage, besides that I am genuinely less interested on the other companies' offers. However I am not sure of how to deliver that answer.
On one hand I think it might give the impression of someone who did not make his mind up for their particular company and is only trying to get a job. Also in that case I don't know if it is fair for the other companies you are interviewing with to name them. On the other hand, I think it may help to give the sense of urgency needed to make the startup decide faster and to let them know that I am someone "marketable" who is not there only because it is the only chance he had.
Are there any general DOs and DONTs for this kind of question?