Macao's bid under the name of Historic Center of Macao has been designated as China's only nomination this year to apply for the inscription on the World Heritage List of the United Nations Educational, Scientific and Cultural Organization (UNESCO).
Macao preserves China's largest clump of urban historical properties, as it had nearly five centuries of uninterrupted contact between East and West, after the Portuguese navigators settled in Macao in the mid- 16th century.
The Historic Center of Macau embraces 12 priceless cultural heritage sites, including China's oldest church, Christian cemetery, lighthouse and western theater.
During what session of the World Heritage Committee was China awarded its 31st World Heritage Site, the Historic Center of Macao？

A. 29th.
B. 30th.
C. 28th.
D. 31st.