Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Until recently the Grand Canyon was thought to be about 5-6 million years old. Recently a scientist gathered data and wrote a paper for a scientific journal that indicated the canyon is about 17 million years old. Before this new information about the canyon is accepted, which of these needs to occur?
Many scientists need to evaluate the data.
Peer review and publication.