Sustainable development is very important when tourism planning is considered, write a 400 words essay explaining your understanding about the following principles giving examples when possible (100 words each principle)1-The idea of holistic planning, cross-sectoral planning and strategy making.2-The importance of preserving essential ecological processes3- The need to protect both human heritage and biodiversity4-The requirement that development should be carried out so that productivity does not deplete resources for the long term and future generations.