What kind of B cells and T cells do not react to pathogens upon the first invasion, but attack it if the pathogen Invades again? A. Killer cells
B. Antibodies
C. Memory cells
D. Red blood cells

So i have a lot of answers answered but it says i still need to answer more questions. why is it doing that? how many questions need to be answered?

There is only one copy machine at your office. you have to make 1000 copies of an expense report. after you begin copying, two other employees show up in the copy room. each has to make only 10 copies each. what is the proper etiquette in this situation?

The only part of the body that should touch the ball when setting in volleyball