Final answer:
A contest was held to find an architect who could design a dome that wouldn't collapse under its own weight. Renaissance merchants responded to challenges by organizing competitions to stimulate innovation.
Step-by-step explanation:
The contest for the design of the dome of the Santa Maria del Fiore cathedral in Florence was held because no architect knew how to construct a dome that wouldn't collapse under its own weight.
Renaissance merchants responded to the idea of something being impossible or difficult to accomplish by organizing a competition and offering a cash reward to stimulate innovation and find a solution.