In the sentence 'The rational is rewarded'. Why is rational an adjective in the sentence.

Because the word "rational" takes on the function of modifying the noun, in addition to representing a characteristic.

Explanation:

Adjectives are words that accompany a noun and modify it, adding a characteristic that particularizes that noun. In this case, we can say that in the sentence above, the word "rational" is the adjective, since it specifies what is "rewardable".

It should be noted that adjectives accompany nouns in number, gender and degree.

innocence can be defined as the lack of sin, relating it with the lack of guilt, also it can be a synonime of naivety. most people agree that sins are made out of experiences, intentionally or not, as well as you stop being naive once certain things happen to you throughout your life. so, with this explained, the chosen answers are:

when the boy saw the effects of war, he no longer viewed life as innocent.

the loss of innocence is a result of gaining experience and making mistakes.

one way to define innocence is as a lack of worldly experience or sophistication.