$6.$ Suppose you're a consultant for the Ergonomic Architecture Commission, and they come to you with the following problem. They're really concerned about designing houses that are "user friendly," and they've been having a lot of trouble with the setup of light fixtures and switches in newly designed houses. Consider, for example, a one$-$floor house with n light fixtures and n locations for light switches mounted in the wall. You'd like to be able to wire up one switch to control each light fixture, in such a way that a person at the switch can see the light fixture being controlled. Exercises $41723($a$)$ Ergonomic $($b$)$ Not ergonomic