Lamarck wrote an important book talking about. a. the old age of earth. b. how organisms could change. c. the movement of the continents. d. that fossils were extinct organisms.

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).