Step 1: Understanding the Concept
de Broglie proposed that a moving particle has a wavelength \(\lambda=\dfrac{h}{p}\).
Step 2: Analyse the relation
Here \(h\) is Planck's constant, so \(\lambda\propto\dfrac{1}{p}\).
Step 3: Compare the options
The wavelength is inversely proportional to momentum, which is option (C).
Final Answer:
The de Broglie wavelength is inversely proportional to the momentum of the particle.
\[ \boxed{\text{(C) }\text{is inversely proportional to momentum}} \]