Step 1: Understanding the Concept.
Nalanda University, an ancient centre of learning in Bihar, was revived as a modern international university with support from several Asian countries, since it had strong historical links to the region.
Step 2: Check the options.
Japan, Singapore, and Malaysia were all part of the broader group of countries supporting the Nalanda revival project, but the specific one billion US dollar aid announcement referred to here came from a different country, so options A, B, and C do not match this exact fact.
Step 3: Final Answer.
China announced this one billion dollar aid pledge for Nalanda University's reconstruction, so option D is correct.