Select the correct indirect form of the given sentence.

“Let us go to the hills for a vacation,” Mother said to us.

Mother suggested that we should go to the hills for a vacation.

The correct indirect form of the given sentence is:

Mother suggested that we should go to the hills for a vacation.

The other options are incorrect:

• Mother said that should we go to the hills for a vacation. This is incorrect because we use the word "should" to express obligation, not suggestion.
• Mother ordered us to go to the hills for a vacation. This is incorrect because the reported speech is a suggestion, not an order.
• Mother suggested that let us go to the hills for a vacation. This is incorrect because we do not use the word "let" to introduce suggestions in indirect speech.