After the skin is cut and a capillary wall breaks, what's the first step in working to form a clot?
a. a set of reactions are triggered.
b. thrombin causes sticky fibrin filaments to form the clot.
c. the clot seals the area to prevent further blood loss.
d. platelets clump at the site.

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

Advances in technology have enabled scientists and researchers to better study the evolutionary relationships between species

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.