Step 1: Understanding the Concept
A tooth has hard outer layers (enamel, dentine, cementum) around a central pulp cavity.
Step 2: The pulp
The pulp is soft connective tissue that enters through the root canal. It carries blood vessels and nerve fibres.
Step 3: Other options
Calcium salts make enamel and dentine. Cementum covers the root. These are not pulp contents.
Final Answer:
The pulp contains blood vessels and nerve fibres.
\[ \boxed{\text{(C) }\text{blood vessels and nerve fibres}} \]