What techniques were used to determine the evolutionary relationships among species of flightless birds?
a. DNA samples and morphological data was only available for living species, so their relationships to extinct species were deduced by educated guesses.
b. DNA samples could only be obtained for living species, so their relationships to extinct species were deduced using only morphological data.
c. Morphological measurements were taken and compared for both living species and museum specimens of extinct species.
d. DNA samples from both living species and museum specimens of extinct species were sequenced and compared.