TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: Constructive forces type of forces are involved when deposited rock forms deltas or barrier islands.

SOLUTION: What type of forces are involved when deposited rock forms deltas or barrier islands?

PROBLEM: A bow wake is created when the wave source moves faster than the wave propagation speed.

SOLUTION: What is created when the wave source moves faster than the wave propagation speed?

PROBLEM: Lipids are available to the body from three sources.

SOLUTION:
Lipids are available to the body from how many sources?