The correct answer is:

He proposed that they should wait for the award.

When converting a direct speech sentence to indirect speech, we need to make the following changes:

• Remove the quotation marks.
• Change the reporting verb to one that is appropriate for the mood of the sentence in direct speech. In this case, the reporting verb "said" is changed to "proposed" because the sentence in direct speech is an imperative sentence.
• Change the pronouns to match the subject and object of the reporting verb. In this case, the pronoun "I" in the direct speech sentence is changed to "they" in the indirect speech sentence because the subject of the reporting verb is "he" and the object is the group of people that he is speaking to.
• Change the verb tense to match the tense of the reporting verb. In this case, the verb tense in the direct speech sentence is present tense, so the verb tense in the indirect speech sentence is also present tense.

Therefore, the correct indirect speech sentence is:

He proposed that they should wait for the award.