A population of frogs in a pond began with 67 individuals. Over one year, the population changed to 53. Which are two possible reasons for the change within the frog population?

emigration or increase in death rate
emigration or increase in birth rate
immigration or decrease in death rate
immigration or increase in birth rate

PLZ HURR 20 POINTS

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.