B. elegance (The sentence discusses the comfort and visual appeal of the hotels and ships, making "elegance" the most suitable word.)

B. threat (The sentence indicates that mass tourism can be harmful to historical places, so "threat" is the most appropriate word.)

A. each (The phrase "each and every" emphasizes the occasional nature of the visits.)

D. attraction (The sentence is discussing the main feature that draws tourists to the park, making "attraction" the correct term.)

B. preservation (The sentence discusses the good condition of the heritage sites, making "preservation" the most fitting word.)

B. excavation (The sentence describes the discovery of an ancient settlement, making "excavation" the correct term for the archaeological work.)

A. scenery (The sentence describes the visual beauty of the setting, making "scenery" the most appropriate word.)

C. students to smoke (The verb "allow" requires an object + infinitive structure, making "students to smoke" the correct form.)

D. ran (The sentence describes a completed action, making the past simple form "ran" the correct choice.)

A. park (The sentence describes the action of parking the car, making the base form "park" the correct choice after the verb "watched.")

D. to visit (The phrase "planning to" requires an infinitive form, making "to visit" the correct choice.)