TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Lichens are not a single organism, but rather an example of a mutualism.

SOLUTION: Lichens are not a single organism, but rather an example of a what?

PROBLEM: A(n) gastropods is noted for having its eyes at the tips of stalks or tentacles that emerge from its head.

SOLUTION: What type of creature is noted for having its eyes at the tips of stalks or tentacles that emerge from its head?

PROBLEM: Horse of these most likely has the greatest mass.

SOLUTION:
Which of these most likely has the GREATEST mass?