1. A student studies feeding relationships among sea otter, sea urchins and the abundance of kelp. Sea otters pray on sea urchins and urchins eat kelp. The student measured the kelp abundance at 4 different sites, then spent a day at each site and marked whether otters were present or absent every 5 minutes during daylight hours. (a) Construct a graph that shows how otter density depends on kelp abundance, using the data shown above