Which 18th-century spiritual elder and hermitage, located in the Kaluga region, became a major centre of Orthodox spiritual revival and inspired Dostoevsky's Father Zosima in 'The Brothers Karamazov'?

• A Sarov Monastery
• B Diveyevo Convent
• C Valaam Monastery
• D Optina Monastery ✓

The Optina Pustyn monastery was renowned for its startsy (spiritual elders) in the 19th century; figures like Ambrose of Optina attracted pilgrims including Gogol, Dostoevsky, and Tolstoy.