Afew 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

Physical

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 a physical barrier.

It presents a physical stimuli since these characteristics of the skin isn't optimal for the mold spore to survive and benefit from. It is not biological since the barrier isn't an intrinsic obstacle and not a chemical barrier since these can still be manifested in a molecular view, it is just the absence of the needed resources for the pore to survive.

When you are making a guess you are forming a hypothesis