The finches on the Galapagos Islands
were similar in form
except for variations in
their beaks. Darwin
observed that these
variations were useful
for
A. Attracting a
mate
B. Defending
territory
C. Building nests
D. Gathering food

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

the correct answer is d

a researcher conducts an experiment on the secretion of a particular hormone in mice. scientists inject mice with a substance that stimulates the production of the hormone. the scientists then test the levels of hormones produced by the mice. the tool used to measure the hormones consistently detects the levels at 10 points lower than the actual hormone levels in the mice. this tool makes measurements, but the measurements aren't .

explanation:

no u