Final answer:
During gestation, a fetus does not have any commensal microorganisms on their skin or mucosal surfaces. Option e.
Step-by-step explanation:
The correct statement in the options provided is e. During gestation in mammals, a fetus does not have any commensal microorganisms on their skin or mucosal surfaces.
Commensal microorganisms are those that live on or in the body without causing harm. However, during gestation, a fetus is sterile and does not have any commensal microorganisms on their skin or mucosal surfaces. The colonization of commensal microorganisms begins after birth.
The other statements are correct. Mucosal surfaces, such as the respiratory tract, gastrointestinal tract, and genitourinary tract, are better than skin surfaces at supporting colonization by commensal microorganisms (option a). The skin provides a larger surface area than mucosal surfaces for commensal microorganisms (option b). There are indeed ten times as many bacteria residing in the intestinal tract than the number of cells in the human body (option c). It is common for commensal bacteria to live in symbiosis with their human hosts, benefiting both the bacteria and the host (option d).