Read the following passage and mark the letter A,B,C or D to indicate the correct answer for each of the blanks. 

The citadel of the Ho Dynasty was built according to the Feng Shui principles, (1) ____ the flowering of neo-Confucianism in the late 14th century in Viet Nam and its spread to other (2) _____ of East Asia.  According to these principles, it was located in a landscape of great (3)______ beauty on an axis (4) _____ the Tuong Son and Don Son Mountains in a plain between the Ma and Buoi Rivers. In terms of architectural history, the citadel of the Ho Dynasty (5) ______ an important role in the planning and building of urban areas in Viet Nam. It shows the uniqueness (6) _____ the constmction of a citadel in general and a stone citadel in particular, and a breakthrough in Viet Nam’s tradition of citadel building.

Thanks to the unique construction techniques, all the (7) _____ stone sections are intact and have not been (8) _____  by time and weather or by recent urban encroachment. The citadel of the Ho Dynasty is an architectural (9) _____ of the 14^th century with impressive architecture of the walls and other parts. The citadel buildings represent an outstanding example of a new (10) ______  of Southeast Asian imperial city with a combination between the Vietnamese architecture and the unique building techniques of Southeast Asia and Eastern Asian.

… have not been (8) _____  by time and weather or by recent urban encroachment.