The two correct answers are
The coral reef now has more protection against deposition and the coastline now has less protection against erosion.
Step-by-step explanation:
Deposition refers to building up of layers of sediments, soil and rocks due to various reasons. Coral reef going deeper under water is now more immune to getting depostied with soil, rocks and sediments and hence has more protection against deposition.
Erosion refers to soil getting ruined due to natural agents. Coral reefs protected the coasts from waves, storms and floods by acting as intermediary or barrier between coasts and storms. Them going deeper into water thus will result in the coastline having less protection against erosion