The correct answer C. Pectinoid is the most occurring fossil that is a bivalve. They are a superfamily of marine bivalve mollusks which includes scallops and oysters. Members of this family have a triangular resilium.
The reason why the year consists of 365 days is because it takes 365 days for our planet to make one full revolution around the sun and the reason why the day consists of 24 hours is because it takes 24 hours for our planet to make one full rotation.
