Parathyroid hormone: a. increases osteoblast activity to release more calcium ions into the bloodstream b. increases osteoclast activity to release more calcium ions into the bloodstream c. increases osteocytes activity to release more calcium ions into the bloodstream d. none of the above

(select all the correct choose each statement that is scientific. - the opinions of randomly selected participants in a survey prove the idea that global temperatures are not increasing on earth. - the universe's average temperature and rate of expansion support the idea that it began as one super-dense and hot mass 13.8 billion years ago. - ocean tides are caused by the uneven gravitational pulls of the moon and sun on different parts of earth. - human life is more valuable than other forms of life on earth because humans are more intelligent than other organisms.