Which 1918 orthographic reform, among other changes, eliminated the letter Ѣ (yat), the hard sign at word-final positions, and the letter Ѳ (fita)?

• A The Petrine script reform
• B The Lomonosov grammar
• C The Bolshevik spelling reform ✓
• D The Grot codification

Though drafted before the revolution, the reform was implemented by the Bolshevik government; it dramatically simplified spelling and is still resented by some traditionalists.