Assume that you are looking at a case of lethal alleles. Crossing two green corn plants results in 2/3 green progeny. If you crossed two green progeny with each other, how many of the progeny would you predict to be green?
a) 1/3
b) 3/4
c) 1/4
d) 4/4

2/3 of the progeny would be green

Explanation:

Lethal alleles means that their presence result in death of the organism

Assuming this Lethal allele is recessive --> a

This way, if there is AA or Aa the plant will survive, otherwise if there is aa the plant will not survive    

Than, assuming AA is a progeny white and Aa is green

Aa x Aa

2/3 Aa - Green

1/3 - White

1/3 - plant will not survive

Crossing 2 green progeny with each other

Aa x Aa

2/3 - Green

i think the miocene epoch spans the time from 23 million to 12 million years ago.