Raven is a painter and is by a river working on a painting of a sailboat catching the wind. Later that afternoon at a coffee shop, Raven meets an aeroscience engineer who is working on the design of a long$-$distance spacecraft that needs an innovative propulsion system. Later that evening, an idea struck Raven, and he begins developing a space sail that propels spacecraft forward by catching light. The strategy for innovation applied by Raven was

making associations.

breaking mental set.

seeking varied input

cross stimulation.