Enzyme that breaks down proteins in the stomach;
A liver
B enzymes
C pepsin
D amylase

Pepsin

Explanation:

Pepsin is the chief digestive enzyme found in the stomach. It breaks down proteins and polypeptides

c. Presence of various elements in the metallic crystal structures is the main contributor to its densely packed structure

d. Metal's crystalline structure tends to be densely packed.

e. Anisotropic materials have their properties varying with the direction of measurement.

Explanation:

a. Isotopic properties are the characteristics of polycrystalline materials.

False because crystalline solids are anisotropic in nature because some properties like refractive index change in different direction in crystalline solids .

b. The crystal structure of metals is very complicated

false - crystalline solids have fixed and ordered pattern. so it has simple structure .

c. false - there is only one element . packed structure is because of short bond length .

d.  true - metals are closely packed and in order manner

e.  true - they have different properties in all direction like electrical conductivity and refractive index

f.  False - metallic bonds are indirectional in nature .