Concept:
Repatriation means returning a person to his or her own country. In legal terminology, it often relates to transfer of prisoners between countries.
Step 1: Understand the objective of the Act.
The Repatriation of Prisoners Act, 2003 was enacted to allow prisoners convicted in foreign countries to serve the remaining part of their sentence in their home country.
Step 2: Understand its humanitarian purpose.
The Act helps prisoners remain closer to their family, language, culture, and social environment, thereby improving rehabilitation opportunities.
Step 3: Eliminate incorrect options.
Options B, C, and D discuss general welfare or rehabilitation measures but do not relate to international prisoner transfer.
Step 4: Conclude the answer.
Hence, the correct answer is:
\[
\boxed{\text{Transfer of foreign national prisoners between countries}}
\]