What is required regarding hats in the building?

The requirement regarding hats in the building is that they must be removed when entering. This practice is often rooted in cultural norms and etiquette which value respect for shared indoor spaces. Removing a hat upon entering is considered polite, especially in places like homes, formal establishments, or certain public buildings where decorum is expected. This action also helps prevent any obstruction or distraction that wearing a hat could cause in social or professional interactions.

The other options do not align with such customary practices involving hats indoors.