Mendel accounted for the observation that traits which had disappeared in the f1 generation reappeared in the f2 generation by proposing thata) new mutations were frequently generated in the f2 progeny, "reinventing" traits that had been lost in the f1.b) the mechanism controlling the appearance of traits was different between the f1 and the f2 plants. c) traits can be dominant or recessive, and the recessive traits were obscured by the dominant ones in the f1.d) the traits were lost in the f1 due to dominance of the parental traits. e) members of the f1 generation had only one allele for each trait, but members of the f2 had two alleles for each trait.