Select the correct indirect form of the given sentence. He said, “I will go to Indonesia tomorrow".

He said that he would go to Indonesia the next day.

The correct indirect form of the given sentence is: He said that he would go to Indonesia the next day.

The other options are incorrect:

• "He said he would go to Indonesia by tomorrow." is incorrect because the preposition "by" is not necessary.
• "He said that he would be going to Indonesia the next day." is also correct, but it is a more elaborate way of saying the same thing.