The builder of a house on a cliff overlooking the ocean should be concerned about whatgeologic phenomenon?

Erosion

Explanation:

Building a house on a cliff is a very trick thing. The cliffs usually are not composed of hard rocks, but instead are usually composed of sedimentary rocks which are much softer and less stable on the long run. The cliffs are also exposed to heavy erosion, in the lower parts because of the waves, in the higher parts because of the winds. The erosion makes the cliffs slowly fall apart, and occasionally even crumble down, so a builder that would build a house on a cliff should be wary of all these things and construct the house where it is the safest for the long run.

the wrong statement is - c. a desert had more biodiversity than a marsh.

the deserts are one of the places of the planet where there's the least biodiversity. the reasons for that are the climate and the lack of food sources, which hampers both the number of the species that can survive in it, and the number of the individuals in the species itself.

the marshes, on the other hand, are places where there's perfect conditions for lots of organisms to thrive. the temperature is moderate and nice, the amount of water and the food sources are on a high level, so there's an abundance of both plant and animal life in them.