When sufficient heat is applied, double-stranded DNA denatures into two single-stranded molecules as the heat breaks all of the hydrogen bonds. In an experiment, molecules of single-stranded DNA from species X are separately hybridized with putatively homologous single-stranded DNA molecules from five species (A-E). The hybridized DNAs are then heated, and the temperature at which complete denaturation occurs is recorded. Based on the data below, which species is probably most closely related to species X? Species Temperature at Which Hybridized DNA Denatures
A 30°C
B 85°C
C 74°C
D 60°C
E 61°C

a. Carbohydrates; poorly conserved.
b. Fatty acids; highly conserved.
c. Lipids; poorly conserved.
d. Proteins or nucleic acids; poorly conserved.
e. Amino acids; highly conserved.