Answer:
D. a red allele present on at least one of two homologous chromosomes;
D. unplanned ecosystem interactions
Explanation:
A dominant allele or trait would always mask the expression of a recessive trait when both are present in a pair. The only way a recessive trait can express itself is when it is in a homozygous state. Since red color is dominant over white color in the beetle species, the genotype of any red color species would have a red alelle present on at least one of two homologous chromosomes. For example, if red allele is represented by R and white allele is r, the genotype of a red nettle species would be RR or Rr.
In the second question concerning the most reason for concern that some scientists recommends caution be taken regarding genetically modified plants is that in the process of introducing new genes into a population, unforseen and unplanned disruption of the ecosystem may occur as a result of interaction with the ecosystem that these process and it's product may present.