Plankton are most commonly found in the a. pelagic zone b. littoral zone c. benthic zone d. all of the above

Explanation:The answer is a: pelagic zone

Planktons are most commonly found in the pelagic zone.

Planktons are organisms that have their habitation in large bodies of water. They are source of food to large aquatic organisms like whales and so on. They are also organisms that spend all or part of their lives drifting freely in water.

Pelagic zone can be referred to as an area or region of a body of water.