The Tropic of Capricorn is an imaginary line of latitude that runs approximately 23.5 degrees south of the equator. It marks the southernmost point at which the sun can be directly overhead at noon. The Tropic of Capricorn passes through several countries, including Botswana, Swaziland, Zimbabwe, and Zambia. However, the correct answer to this question is Botswana.

Reasoning:
- The Tropic of Capricorn passes through Botswana, making it the only country in the given options that the line crosses.
- Botswana is located in southern Africa and is bordered by South Africa to the south and southeast, Namibia to the west and north, and Zimbabwe to the northeast. The Tropic of Capricorn runs through the central part of the country.

Other Options:
- Swaziland: Swaziland, officially known as Eswatini, is a landlocked country located in southern Africa. However, the Tropic of Capricorn does not pass through Swaziland.
- Zimbabwe: Zimbabwe is a landlocked country located in southern Africa, bordered by South Africa to the south, Mozambique to the east and northeast, and Botswana to the west and southwest. The Tropic of Capricorn does pass through Zimbabwe, but it also passes through Botswana, which is the correct answer.
- Zambia: Zambia is a landlocked country in southern Africa, bordered by Tanzania to the northeast, Malawi to the east, Mozambique to the southeast, Zimbabwe and Botswana to the south, Namibia to the southwest, Angola to the west, and the Democratic Republic of the Congo to the north. The Tropic of Capricorn does not pass through Zambia.

Conclusion:
In conclusion, the Tropic of Capricorn passes through the country of Botswana. It does not pass through Swaziland, Zimbabwe, or Zambia.

It's a line which runs parallel to the equator, but 26-degree 30" south of it.