Question

a few mold spores land on the skin but do not survive due to the lack of moisture and the presence of oxygen. these spores have been prevented from harming the body by which type of barrier?
biological
chemical
physical
mechanical

Explanation:

Chemical barriers in the body can include factors like the lack of moisture (which can inhibit microbial growth) and the presence of substances (in this case, oxygen might be part of the chemical environment that is not favorable for the mold spores). Physical barriers are more about structure (like the skin itself as a physical layer), biological barriers involve living cells or organisms (like immune cells), and mechanical barriers are more about movement or physical forces (like cilia moving substances). Since the question mentions lack of moisture (a chemical - related factor in terms of the environment for the spores) and presence of oxygen (a chemical), it points to a chemical barrier.

Answer:

chemical