✅ When a statement in direct speech is in the Present Perfect tense, it changes to the Past Perfect tense in indirect speech.

The verb "have completed" correctly shifts to "had completed."

The pronoun "I" also changes to "he" to reflect the speaker (the student).

❌ Option A incorrectly shifts to Simple Past, rather than Past Perfect.

❌ Option C does not shift the tense at all, which is usually required when the reporting verb is in the past.

❌ Option D introduces a conditional future tense ("would complete"), which alters the original meaning and tense.

✅ In reported speech, the Simple Past tense ("submitted") usually shifts to the Past Perfect tense ("had submitted").

✅ The time expression "last week" correctly changes to "the week before" in reported speech.

❌ Option A retains the Simple Past tense and "last week," which is incorrect for reported speech.

❌ Option C uses the Simple Present tense ("submits"), which is a wrong tense shift.

❌ Option D uses "would submit," which implies a future action in the past, altering the original meaning of a completed action.