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.

C.

Explanation:

Mendel observed that some traits that were visible in the phenotype of F2 offspring were not visible in those of the F1  generation, but he concluded the invisible traits were nonetheless present despite their not being expressed or visible. He hypothesised that some traits were able to cover or hide others and he called the former "dominant" and the latter "recessive" and concluded that when both traits were together in the same individuals, the dominant ones did not allow the recessive ones to be expressed, which could only become visible in the next generation in the individuals where the dominant traits were not present.

this age may represent the age of the earth's accretion, of core formation, or of the material from which the earth formed. this dating is based on evidence from radiometric age-dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.