Which of the following statements is true?

A. Thin wedges need more effort than thick wedges to do work.
B. Second-class and third-class screws have very wide threads.
C. In a second-class lever, the load is between the fulcrum and the effort.
D. All of the above.

answer; /// the correct )

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.