Answer:
C. Phenotypes
Explanation:
Taking notes on all the physical characteristics observed about the tortoises and then observing the finches, I have observed the phenotypes.
Phenotypes are the observable characteristics of a species which are the result of genetic expression influenced by the environmental factors.
So, phenotypes will be recorded during the trip while taking notes on all the physical characteristics which can be directly related to genotype and environmental factors.
Hence, the correct option is "C. phenotypes".