The structure through which air passes on its way from the atmosphere into the vertebrate lung is:

Question 32 options:

alveolus

thymus

esophagus

diaphragm

trachea

Which statements explains what the fossil records indicates? check all that apply. a) earth is 4.5 billion years old b) many organisms have become extinct c) mammals have always existed on earth d) mass extinctions have occurred several times on earth e) the amount of water on earth has decreased over time?