Think Deeper: If stars, and most of the universe, are composed primarily of hydrogen and hellum, then why are all living things on Earth composed primarily of Carbon, Nitrogen, Hydrogen, and Oxygen? Where does this material come from?

Which of the following is part of the explanation or description of electromagnetic waves? (select all that apply) a. electrically charged molecules in a medium transfer their energy to nearby electrically charged molecules. b. a changing electric field causes a changing magnetic field. c. magnetic molecules in a medium transfer their energy to nearby magnetic molecules. d. a changing magnetic field causes a changing electric field.