Final answer:
The country from the options given that has a capital city beginning with the letter 'B' is Belize, with the capital city named Belmopan.
Step-by-step explanation:
The student's question asks which country's capital begins with the letter 'B'. From the options given, the country Belize has the capital city that begins with the letter 'B', which is Belmopan. It's important to know the capitals of different countries for complete geographical knowledge. Additional capital cities that begin with the letter 'B' are Beirut for Lebanon and Brasília for Brazil.