The Tropic of Capricorn is an imaginary line located at approximately 23.5 degrees south of the equator. It marks the southernmost point where the sun can be seen directly overhead at noon on the December solstice. The Tropic of Capricorn passes through several countries in the southern hemisphere.

The correct answer is option 'A', which means that the Tropic of Capricorn passes through country 'a'. Let's explore which country it refers to.

Explanation:
The Tropic of Capricorn passes through the following countries:

1. Australia: The Tropic of Capricorn runs directly through the central part of Australia. It passes through the states of Queensland, New South Wales, South Australia, and Western Australia. Several iconic landmarks in Australia are located along the Tropic of Capricorn, including the town of Rockhampton in Queensland.

2. Chile: A small portion of the Tropic of Capricorn passes through the northernmost region of Chile. Here, it crosses the Atacama Desert, one of the driest places on Earth.

3. Brazil: The Tropic of Capricorn intersects Brazil near the city of São Paulo. It then passes through the states of Minas Gerais, Goiás, and Mato Grosso do Sul before exiting the country.

4. South Africa: The Tropic of Capricorn cuts through the northern part of South Africa, passing through the Limpopo Province. It is marked by the Capricorn Monument, a popular tourist attraction.

Conclusion:
In summary, the extension of the Tropic of Capricorn passes through multiple countries, including Australia, Chile, Brazil, and South Africa. Therefore, the correct answer to the given question is option 'A', which represents one of these countries.