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.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.