Concept:
Malnutrition is caused by multiple interconnected factors including social, dietary, and awareness-related issues.
Step 1:Analyze statement A.
Poor sanitation and lack of clean drinking water lead to infections and poor nutrient absorption.
\[
\Rightarrow \text{Correct} \quad \checkmark
\]
Step 2:Analyze statement B.
Lack of a balanced diet directly causes nutrient deficiencies.
\[
\Rightarrow \text{Correct} \quad \checkmark
\]
Step 3:Analyze statement C.
Lack of awareness leads to poor food choices and improper nutrition.
\[
\Rightarrow \text{Correct} \quad \checkmark
\]
Final Answer:
\[
{\text{A, B and C}}
\]