Answer:
3rd or 4th one
I don't know the exact sry
The mystery food sample did not test positive for protein using the Biuret indicator, so the sample can not be tofu, which is what Zack ate.
The lymphatic system destroy harmful substances 'By producing antibodies'.
The lymphocytes contained in lymphatic organs are produced with other defence cells by the bone marrow. They are then dispersed to eliminate pathogens.