Which statement about “kulla safīnatin ṣaḥīḥatin” is correct?

Ījāz al-Ḥadhf: Forms of Ellipsis and Evidence for Recovering the Omitted

• These exact words occur in the Qur’an
• It is a strictly identical replacement for the verse
• It is merely a technical nautical translation
• It is an explanatory reconstruction, not additional Qur’anic wording