The word ‘their’ in paragraph 2 refers to .

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 34 to 40
Over the past decade many priceless heritage sites and monuments have been damaged in countries across the world. In Africa, sites in Libya, Algeria, Egypt and Mali, among others, have been damaged during internal and cross-border conflicts. The three main threats to heritage sites are development projects, armed conflicts and natural disasters. International agencies like UNESCO have called for the protection of heritage resources in the event of conflict. But this has not happened.
Destroying monuments is a violent act. Those responsible are trying to erase - by force - an aspect of history. One example was the Nazis who, during World War II, tried to destroy Jewish people’s art and personal property. The attacks on monuments and calls for their destruction reflect the systemic and complex violence in many African states, although it’s important to note that the problem is not only an African one. ISIS is the latest group destroying history and heritage. This is popular in Iraq. Syria is another country witnessing its heritage being wiped out. When examining the ongoing conflict in the north of Mali, it is clear that heritage sites are just part of the damage of human lives and cultural property in the ongoing conflict.
It is worth considering national and world heritage conservation policies and guidelines. All heritage is valuable and should be protected. Destroying heritage is not in the interest of humanity. The African continent has to address the question of how we collectively deal with difficult and damaged heritages. A reflection on the UNESCO Conventions between 1954 and 1972 should also provide guidance on future actions on heritage management at local and national levels. The 1954 Convention which calls for the protection of cultural heritage during conflict and war was regularly mentioned during the Iraq conflict and recent conflict in Mali. The 1970 and 1972 Conventions draw attention to protecting world heritage by state parties, with these tools, countries should have enough guidance to individually and collectively protect heritage resources.
Adapted from theconversation.com