Reported Speech, also known as Indirect Speech, involves reporting what someone else said, often requiring changes in tenses, pronouns, and time expressions. Analyze the following statements about backshifting:

I.When reporting a statement made in the Present Simple, the verb usually shifts to the Past Simple if the reporting verb is in the past.

II.The Modal Verb 'must' always remains 'must' in Reported Speech, as it is impossible to express obligation in a reported past context.

III.Time expressions like 'yesterday' are typically changed to 'the day before' or 'the previous day' to maintain the correct chronological reference.

Regarding these statements, select the correct alternative: