Which statement constitutes a research finding that supports the argument that insights do not occur in a sudden, all-or-nothing manner, but instead reflect incremental unconscious processes?

A) People who experience insight later can report the steps that led to the solution if they are asked to reflect on the process.
B) People are able to accurately predict that they are on the verge of an insightful solution.
C) People most often solve problems insightfully during altered states of consciousness.
D) People can accurately determine if an insight problem has a solution or not, even if they cannot solve the problem.

D) People can accurately determine if an insight problem has a solution or not, even if they cannot solve the problem.