Step 1: Idea:
Phenol is very reactive, so bromine water needs no Lewis acid.
Step 2: Product:
Three Br atoms enter at positions 2, 4 and 6.
Step 3: Look:
This solid does not dissolve in water, so a white precipitate shows. This is also the test used for phenol.
Final Answer:
The product 2,4,6-tribromophenol is a white solid.
\[ \boxed{C} \]