Consider the following levels: (1) chemical; (2) tissue; (3) organ; (4) cellular; (5) organismal; (6) systemic. Which of the following choices has the levels listed in order of increasing complexity?...

Consider the following levels: (1) chemical; (2) tissue; (3) organ; (4) cellular; (5) organismal; (6) systemic. Which of the following choices has the levels listed in order of increasing complexity?

a. 1, 2, 3, 4, 5, 6

b. 1, 4, 2, 5, 3, 6

c. 3, 1, 2, 4, 6, 5

d. 1, 4, 2, 3, 6, 5

e. 4, 1, 3, 2, 6, 5

Which is not essential to survival?

a. Water

b. Oxygen

c. Gravity

d. Atmospheric pressure

e. Nutrients