Usually, alleles that code for a characteristic that is dominant should be presented with an uppercase letter. And by having dominant alleles, it means that no matter if the individual has a recessive allele or not, the characteristic of the dominant allele must be shown.
Therefore, since detached earlobes are dominant, the letter representing for this allele should be E. Uppercase. And if the child has both E and E allele, it's no doubt that the phenotype (characteristics that are shown) should be having detached earlobes. So, your answer should be A. 100%
Even if the child has one lowercase e allele, as long as they have a dominant E allele, they'll still be 100% sure of having detached earlobes. Recessive trait (attached earlobes in this case) is only shown when both alleles of the genotype are recessive (e and e).
