I struggle a lot with pedigrees pls help!

The meselson-stahl experiment demonstrated that dna replication is semiconservative. in the figure, semiconservative replication is illustrated by

What sentence best supports the statement that hormones are involved in the regulation of homeostasis? a. the hormone erythropoeitin increases the production of red blood cells when oxygen levels are low. b. the hormone oxytocin promotes labor contractions of the uterus during childbirth. c. the hormone melatonin induces sleep and its production is slowed by exposure to light. d. the hormone cortisol suppresses the immune system and is produced when the body is under stress.

The cluster of developing cells from conception until birth is called an