You Sample the Solid Waste of Three Infants from Three

Multiple Choice

You sample the solid waste of three infants from three different families each week for 24 weeks. You find that the population of bacteria in the gut is dominated by one species for the first 12 weeks, and then shifts to another species. This suggests the gut bacterial community:

A) is fixed and unchanging.
B) is essential for human health.
C) is harmful to humans.
D) composition changes over time.
E) is helpful to humans.