Answer:
Option C
Step-by-step explanation:
Precipitation indirectly decrease the salt concentration as the water which is precipitated is taken from any water body in fresh form (i.e without any salt) through evaporation. Hence addition of fresh water into any saline water body decreases its salinity
Like wise run off brings in also reduces salinity as it brings in water from different directions to dump it into a saline water body thereby increasing the water volume and hence reducing the salinity
Formation of sea ice leaves behind dissolved salt in water with concentration and hence the salinity of water increases.
Melting of ice do not increase the salt concentration as frozen water is fresh water and as it melts it reduces the salinity of a saline water body.
Option C, formation of sea ice