What should the food handler do before touching the chicken lettuce tomato and bun?

Before the food handler handles any type of food or cooks and prepares them. It is best that they should properly wash their hands in order to prepare them with clean hands. It is best to wash the hands before handling the food so that the hand that could have exposed to dirt could be cleaned and it will prevent the food from being contaminated.

The answer is joseph is observing the colour of the reaction mixture to see whether proteins are present in the given solution.

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.