The part of the brain responsible for speech, thought, and memory is the
medulla
cerebellum
cerebrum
thalamus

Cerebrum

The cerebrum is the largest part of the human brain. The cerebrum serves in a multiple variety of functions like logic, memory. emotions, movement and cognition, perception mostly. It has four lobes, the frontal lobe, parietal lobe, temporal lobe and occipital lobe. 

The student’s scientific question can be an statement of predicting something to happen

answer: - b cells

explanation: -

there are many types of white blood cells present in our body. one such class of white blood cells are the lymphocytes. the b cells belong to the lymphocyte class of wbcs. the b cells perform their action against the pathogen by producing specialised proteins called as antibodies. these antibodies are produced as and when the b cells encounter pathogens in response to the antigens present on the surface of the pathogen. these antibodies bind to the antigens present on the pathogen and then, target them for destruction by other cells of the immune system.

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.