Correct Answer: gave the benefit of doubt

Solution : The first option is the correct choice.

If you give someone the benefit of the doubt , you treat them as if they are telling the truth or as if they have behaved properly, even though you are not sure that this is the case.

The meanings of the other options are as follows:

• Changed his tune means to behave in a different way.
• The expression to err is human, to forgive divine is an expression that means that all humans tend to make mistakes, but it is a godlike characteristic to forgive those mistakes.
• Never judge a book by its cover means never to judge someone or something based on what you see outside without having full knowledge.