Fungi form lichens by living in a close relationship with an algae. The fungus provides a
protective home for the algae, and gathers mineral
nutrients from rainwater and from dissolving the
rock underneath. The algae gathers energy from
the sun using photosynthesis. Both organisms
share their nutrients with each other.
A. Commensalism
B. Parasitism
C. Mutualism
D. Competition

Commensalism

Explanation: Well you can already eliminate parasitism because that is when an organism leeches off another. Mutualism is when one organism needs to depend on another compared to A where both are benefited.  Then you can eliminate d because competition is when two organism compete with each other for survival not benefiting them both.

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a