Why do scientists discuss herd immunity through the lens of vaccination, not natural infections?

Scientist have long study the earths climate by looking at which of the following? the earths orbit. the earths rock layers. the antarctic ice. the earths oceans.

Which best describes meiosis? a. it produces cells that are identical to the original cell b. it is responsible for the replacement of damaged skin cells c. it is responsible for growth of the organism d. it produces male and female sex cells

You see a white marker with an orange circle and black lettering. what does this marker tell you