;urgent.

how do both jetties and seawalls manage beach erosion?

1): both use plants to keep sand on the beach.
2): both bring sand to the beach from offshore.
3): both are hard structures that reduce erosion caused by waves.
4): both provide flood protection in the event of high waves.

Groups of organisms with low biotic potential, such as gray whales, that produce at most one offspring every other year a) are r-selected b) are k-selected c) are not subject to density-dependent limiting factors d) show the initial stages of the extinction process e) have escaped from the processes of natural selection and adaptation

All phases of matter may have a fixed mass

Which of the following sentences has a compound predicate?