Directions: Fill in the blank with the most appropriate of the given options.

Chemical changes that are produced _____________ the curing of tobacco, alter its aroma.

'During' is the only correct preposition to indicate something happening throughout the time period of tobacco curing. 'Amidst' suggests being surrounded by, 'among' requires multiple nouns, 'in' is too vague, and 'between' requires two distinct points. 'During' correctly shows the chemical changes occurring across the entire curing process.