The scope of a research project depends most on the
project's:

The scope of a research project depends most on the resources that are available, like time and available funding.

Explanation:

It is important to take the available amount of resources like time and financing into account when trying to determine the scope of a research project and designing the research question.  The research question will have to feasible in the sense that the question can be answered in the time and with the resources that are available. For example, a wide-reaching survey-based study would not be feasible if there is only one month to collect data and to analyze the results.  It also would not be feasible to study some subject that requires a lot of lab work and expensive testing techniques if there is not adequate funding available.