Which structure is an adaptation that birds break down food?

a.
kidney

b.
gizzard

c.
anus

d.
liver

B. gizzard is specialized in grinding food

I think the correct answer from the choices listed above is option B. Gizzard is the adaptation that helps birds break down food. Similar to a stomach, the gizzard is used to grind up the foods the bird eats. Hope this answers the question. Have a nice day.