Question

which practice can help prevent many diseases?
eating foods rich in gluten
getting blood transfusions
avoiding tobacco products
taking calcium supplements

Explanation:

Tobacco use is linked to numerous diseases like cancer, heart - disease, and respiratory diseases. Avoiding it can prevent many health issues. Eating foods rich in gluten can be harmful to those with celiac disease or gluten - sensitivity. Blood transfusions are medical procedures done when necessary and not a preventive measure for general diseases. Taking calcium supplements is for bone health and not a broad - spectrum disease prevention method.

Answer:

avoiding tobacco products