Answer:
The correct answer is option d) "blood".
Explanation:
The blood is the main tissue that serves as a protection from infectious organisms. Once pathogens enter to the blood, the infection can scale very fast by entering to the organs. However, the blood provide many lines of defense to the body, including cells and molecules. The cells of the immune system include: B-cells, T-cells, neutrophils, macrophages, natural killers; while the molecules include: antibodies, interferons and complement proteins.
