What must be true for a research question to be considered effective?

The question must have a single focus for research from valid sources.
The question must be simple so that any audience will be able to understand it.
The question must have several components to cover as many subtopics as possible.
The question should include the writer's personal views.

The question must have a single focus for research from valid sources. The question must be simple so that any audience will understand it.