Which of the following provides the best example of how comparative embryology supports the theory of evolution? (2 points) a
Humans do not lay eggs as birds do, but birds produce yolk sacs instead of embryos, suggesting birds evolved later than humans.

b
Humans have a tailbone that is visible during embryonic development, which suggests that humans evolved to depend on a useful tailbone.

c
Humans do not have gills as fish do, but human embryos have gill slits, suggesting humans and fish share a common evolutionary ancestor.

d
Humans have stem cells that develop in an unpredictable way, which suggests that other organisms also evolved to develop in the same manner.

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation:

answer///multiple alleles;