In Order to Find New Ways for a Company to Develop

In order to find new ways for a company to develop new products, the CEO asked a group of team leaders to imagine that all of the materials they normally use to make their products were no longer available. In doing so, the CEO is

A) encouraging creativity by defining the problem broadly.
B) discouraging creativity because the problem is defined too broadly.
C) encouraging the use of mental sets, thus, encouraging creativity.
D) imposing constraints or restrictions on thinking to encourage creativity.