Answer:
Explanation:
There are three major branches of biology – botany, zoology and microbiology. Botany is the branch of biology which deals with the study of different aspects of plants.
Just as the organs in an organ system work together to accomplish their task, so the different organ systems also cooperate to keep the body running. For example, the respiratory system and the circulatory system work closely together to deliver oxygen to cells and to get rid of the carbon dioxide the cells produce.
This picture represents humoral immunity, please read through it, and if you dont understand which option is your answer then i would recommend you read more about this topic, if you want it to be done fast, you can read this http://www.s-cool.co.uk/a-level/biology/immunity/revise-it/the-third-line-of-defence
I hope you can come up with the answer on your own as it will be a good thing for you in your future exams :)
Surely i can help you if you dont understand something so just ask :D