How Does the Immune System of Vertebrates Utilize a Chemical

Multiple Choice

How does the immune system of vertebrates utilize a chemical concentration gradient?

A) The immune system produces thousands of histamines that act solely to create a histamine diffusion barrier.
B) The immune system generates a gradient of reactive oxygen intermediates to increase the amount of toxic radicals and peroxides to combat invading pathogens.
C) The immune system releases chemical signals called chemokines, which create a chemical gradient that leukocytes use in migrating toward the infection site.
D) The vertebrate immune system does not use chemical gradients.