12 people are waiting at a subway stop to get on the train. however, the train only has space for 9 people to board. how many different combinations of people can get on the train?

Summarize the work of famous environmental scientists of the past.

Ineed so much with both of these tot

Adult wasps sting caterpillars and inject their eggs into the caterpillars. the larvae feed on the caterpillars, leading to the death of the caterpillars. what kind of a relationship exists between the wasps and the caterpillars? a. the adult wasps are parasites to the caterpillars. b. the caterpillars are parasites to the wasps. c. the adult wasps are commensals, and the caterpillars are hosts. d. the caterpillars are commensals, and the adult wasps are hosts.