Why organs fully develop during adolescence and not right from the birth of an individual?

The reason behind this is because  the major difference between childhood and adulthood is sexual maturity and during transitional stage of adolescence , the sex organs devlops.

        hope yhis helps u

The gonads (Testes and Ovaries) fully develop during adolescence.

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.