Which of the following is true about the speed of light? O it is a constant when the light is traveling in a vacuum.
O It speeds up or slows down depending on the observer.
O It is slowest in a vacuum.
O lt varies depending on the color of the light.

The theories on the expansion of galaxies maybe re-examined to strengthen science should not be tested to strengthen science will weaken scientific knowledge if they change will become laws if they don't change

Which of the following best describes the purpose of the parathyroid hormone? a. it decreases the blood calcium level and decreases blood phosphorus level. b. it decreases the blood calcium level and increases the blood phosphorus level. c. it increases the blood calcium level and increases blood phosphorus level. d. it increases the blood calcium level and decreases blood phosphorus level.

Electrons are brought to the electron transport system by the oxidation of