Which of these describes a method in studying plate movements? • Collect common fossil evidence from the south American and African plates

•Examine the age of a mountain structure on the African plate only

•Match the size and shape of rocks on the north and south edges of Australia

• Match the rotation of earth to plate movement​

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.