How is parasitism different from commensalism? a. both organisms benefit in parasitism and only one organism benefits in commensalism. b. one organism benefits in parasitism and no organisms benefit in commensalism. c. one organism is harmed in parasitism and both organisms are harmed in commensalism?

Parasitism is when one organism benefits at the cost of it's host. Like fleas on a dog or intestinal parasites to livestock. Fleas and intestinal worms get food and a nice place to livr, while the dogs and the livestock are being leeched off of and malnourished.

Commensalism is when one organism benefits, while the host is left unharmed- but also doesn't really get anything in return, unlike mutualism. Like a shark and remoras (those fish with suction-cup heads & hitchhike). Sharks aren't hurt, but the remoras get free transportation and access to food scraps.

Hope this helps!