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 $1\mathrm{.}2$ billion travellers crossing international borders in $2016,$ and that number expected to grow to $1\mathrm{.}8$ 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?

Demand will increase and supply will decrease.

Supply will increase, but these two factors will not shift the demand curve.

Demand and supply will both increase.

Demand will increase, but these two factors will not shift the supply curve.