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 38

People's need to travel faster, safer, and more efficiently has fueled the invention of great technological solutions. During the last decades, the impact of technology on travel has become even more significant thanks to the application of new IT services, (34)______ to the rise of the online travel market and the increasing digitalization of the travel industry. An important achievement behind the online travel experience dates back to the 1960s (35)______ the first global distribution system (GDS) was introduced. GDSS are online networks connecting suppliers- (36)______ airlines, hotels, or cruise lines - to providers, like travel agencies and online travel agencies. Having access to the suppliers' inventory, like the number of seats or hotel rooms available, GDSS allow providers to (37)______ such information, helping customers book multiple travel services at once. In 2021, the market size of the global distribution system industry worldwide was estimated at approximately six billion U.S. dollars. That year, the air distribution business segment of Amadeus, one of the (38)_______ renowned GDSS worldwide, generated roughly one billion U.S. dollars in revenue.