Explanation:

- Around sixty bands in colourful costumes took part in the Notting Hill Carnival.

- The word "costumes" fits the context of a carnival.

- "Costumes" refers to outfits worn for a specific reason or celebration.

- Carnivals often feature elaborate and thematic costumes.

- Answer: Option 2 - costumes

- "Clothings" is not a standard plural form in this context.

- The correct term would be "clothing" or "clothes," not "clothings."

- "Apparels" is not commonly used in plural form.

- "Apparel" usually refers to clothing collectively, not specific outfits.

- "Dressing" refers to the act of putting on clothes or a style of clothing.

- It does not specifically relate to carnival wear.