Traits Are Sometimes Said to "Skip a Generation

Traits are sometimes said to "skip a generation." How does this happen according to Mendel's experiments?

A) If an allele determining a trait is dominant, recessive alleles from either parent can mask it, like when Mendel's first generation of flowers from a white and purple parent where all purple.
B) If an allele determining a trait is recessive, dominant alleles from either parent can mask it, like when Mendel's first generation of flowers from a white and purple parent were all purple.
C) If an allele determining a trait is recessive, it sometimes just doesn't show up, regardless of what traits the parents have, like when Mendel only got purple flowers in the first generation.
D) Sometimes mutations allow a new trait to mask a recessive trait for one generation. Mendel found this to be the case in his second generation where he got both purple and white flowers.
E) Sometimes a recessive allele is only advantageous after several generations and so doesn't show up until then. Mendel saw this in the white flowers being produced by a cross between purple and white parents.