Solution:
The question asks about entertainment options in big cities. Let's analyze the given options:
- a. Museums, cinemas and art galleries: These are all common forms of entertainment found in major urban centers.
- b. Restaurants and cafes: While also prevalent in cities, these are primarily places for dining rather than entertainment in the same sense as cultural venues.
- c. Parks and recreation zones: These offer outdoor activities and relaxation, which can be considered entertainment, but are not as exclusively tied to the 'big city' concept as cultural institutions.
Considering the typical offerings of large cities, option 'a' most comprehensively represents diverse entertainment venues.
Answer: a. Museums, cinemas and art galleries;