The most likely outcome would be a.temporarily protect the cliff from beach erosion.
Here's the reason why:
As sea wall's construction material is likely to be rock, no matter it's weather-resistance, it would be weathered by different weathering agents, especially in area with relatively high rainfall and humidity. Sea water itself will also catalyse the weathering process by chemical weathering, or physical weathering such as hydraulic action or abrasion.
When the sea wall is not properly maintained or has been in use for a prolonged period, it may be worn off and no longer able to serve as a protection to the cliff.
Therefore, it is a temporary measure to protect the cliff from beach erosion.
Why the other reasons are false:
b. permanently protect the home from beach erosion.
-As mentioned, the seawall can not last forever due to weathering and erosion that can damage the sea wall, the answer is therefore false.
c. increase sediment production on the beach, decreasing the rate of erosion.
-While sea wall may indeed be weathered and produce sediments from the construction material, or slightly help the sediment to accumulate, it is unlikely that it can decrease the rate of erosion effectively.
d. deter biologic activity that might compromise the integrity of the cliff.
Although it is possible to construct a sea wall to prevent biological activity of the cliff, such as the growth of vegetation or being inhabited by creatures, which can damage the integrity of the cliff, a sea wall without proper maintenance may not be able to deter these activities. Besides, it is possible for creatures to reside or plants to grow in sea wall, thus it is not the most likely outcome.
Hope it helps!
