Before Mendel,people Had Observed Inheritance of Dominant and Recessive Traits

Before Mendel,people had observed inheritance of dominant and recessive traits by following many generations of plants and animals.What was different about Mendel's work?

A) He used a plant that had never been cultivated before.
B) He kept careful count of his results, including mathematical analysis.
C) His results were immediately accepted and applied to other studies.
D) He followed more generations than anyone else.
E) He did both cross- and self-fertilizations.