Article Summary World Tourism Day 2017, with Its Official Celebration on September

Article Summary
World Tourism Day 2017, with its official celebration on September 27 in Qatar, was focused on sustainable tourism. Established by the United Nations World Tourism Organization (UNWTO) , World Tourism Day has been celebrated since 1980, and the theme for 2017 was the "International Year of Sustainable Tourism for Development." The event was designed with two sessions: one focused on 'Tourism as a driver of economic growth', and the other 'Tourism and the Planet: committed to a greener future'. With over 1.2 billion travellers crossing international borders in 2016, and that number expected to grow to 1.8 billion by 2030, sustainable tourism is viewed by many as an important catalyst for diversification and economic growth.
Source: Vicky Karantzavelou, " World Tourism Day 2017 celebrated on the theme Sustainable Tourism - a Tool for Development," traveldailynews.com, August 14, 2017
-Refer to the Article Summary.Assume that more global tourist destinations begin to offer and publicize sustainable tourism to American tourists and, due to the growing number of millennials attracted to sustainability, more Americans choose to embrace sustainable tourism.All else equal, what will happen in the market for sustainable tourism as a result of these two factors?

A) Demand will increase, but these two factors will not shift the supply curve.
B) Supply will increase, but these two factors will not shift the demand curve.
C) Demand and supply will both increase.
D) Demand will increase and supply will decrease.