The boy was accused of theft.

The correct answer is C. exonerated.

To exonerate someone is to declare them free from blame or guilt. In the context of the question, the boy was accused of theft, but he was later found not guilty. This means that he was exonerated of the crime.

The other options are incorrect for the following reasons:

• Liberated means to set someone free from captivity or slavery. This does not apply to the boy in the question, who was not in captivity or slavery.
• Impeached means to charge someone with a crime, typically a crime against the state. This does not apply to the boy in the question, who was not charged with a crime.
• Sentenced means to impose a punishment on someone who has been convicted of a crime. This does not apply to the boy in the question, who was not convicted of a crime.