Directions: In each item, choose the word that completes both sentences appropriately.

(I) The library ____________ visitors from bringing food into the reading hall.
(II) Regular exercise ____________ the harmful effects of prolonged stress.

The correct option is curbs.

To choose the correct word that completes both sentences appropriately, let us analyze the meaning of curbs and evaluate how it functions in each sentence:

Definition of Curb: The verb curb means to restrain, control, limit, or keep something in check.

• Sentence (I): "The library curbs visitors from bringing food into the reading hall."
Here, "curbs" is used in the sense of restricting, preventing, or checking visitors from bringing food items into the reading hall.

• Sentence (II): "Regular exercise curbs the harmful effects of prolonged stress."
Here, "curbs" refers to limiting, reducing, or keeping in check the negative physiological and psychological impacts of prolonged stress.

Let us analyze why the remaining options are incorrect:
• expands: Means to increase in size, quantity, or scope, which creates an illogical meaning in both sentences.
• observes: Means to watch carefully or to comply with a law/rule, which does not fit grammatically or contextually in either blank.
• encourages: Means to give support, confidence, or hope. It contradicts sentence (I), as libraries prohibit or restrict food, rather than encourage it.
• celebrates: Means to honor or mark a significant occasion, which does not make sense in either sentence context.

Thus, curbs is the only word that fits both sentences accurately and logically.