What did Levine and McGuinnis observed the antennapedia gene use to light up the antennapedia gene to be able to observe when the gene was being turned on and off during development of the body

According to the article, what valid claim came from the national research council? there is no association between fluoride exposure and increased cancer risk in humans. there is a possible link between fluoride exposure and increased cancer risk in humans. there is a definite link between fluoride exposure and increased cancer risk in humans.