Nutrients and waste are exchanged between osteocytes through the a) bony matrix b) many canaliculi c) haversian canals d) collagen fibers

The correct answer is option B, that is, many canaliculi.  

The fundamental unit of a compact bone is an osteon that is also called a Haversian system. The Haversian system exhibits a cylindrical composition, which comprises of four components, that is, the Haversian canal, lamellae, lacunae, and canaliculi.  

The lacunae are associated together with the help of minute channels known as canaliculi. The canaliculi offer passages through which nutrients can reach the osteocytes and waste components can leave them.  

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.