Why is it impossible to predict the phenotype of the offspring by observing only the phenotype of the two parents?

Because some trait's phenotypes don't indicate their genotypes so in order to predict the phenotype of the offspring you have to know the genotypes of the parents

In the process of meiosis, alleles separate and are added to the gametes in an independent manner. While each gamete (egg or sperm cell) therefore contains one allele for each gene, it's impossible to know which allele, because alleles segregate in a random manner. However, it's possible to calculate probabilities that the offspring will have a given allele using Punnett squares.

Explanation: PENN FOSTER

the answer is c) abandoned properties that are contaminated with hazardous materials.