When a sufficient number of individuals in a population are immune to a disease, as would occur if a large proportion of a population were vaccinated, herd immunity is achieved. that means that if there is random mixing of individuals within the population, then the pathogen cannot be spread throughout the population.

This statement is true

Explanation:

While this question can appear incomplete, the claim stated is in fact true. There are many people who are deciding that they do not want to vaccinate their children, and this can be bad for herd immunity.

What herd immunity is, is that if 90% of kids in a population are vaccinated (cannot transmit the disease), and they are all spread out, statistically speaking, there is very little chance of that 10% of kids meeting each other.

pathogens is the answer

the plates spread at mid-ocean ridges (they are divergent plate boundaries) which allows magma to rise through the weakness between the plates. the magma then emerges as lava from the boundary and cools, creating a new crust.