Which of the following language AI-Biruni did not know?

Greek

The correct answer is Option (4) → Greek

Al-Biruni was born in 973 , in Khwarizm in presentday Uzbekistan. Khwarizm was an important centre of learning, and Al-Biruni received the best education available at the time. He was well versed in several languages: Syriac, Arabic, Persian, Hebrew and Sanskrit. Although he did not know Greek, he was familiar with the works of Plato and other Greek philosophers, having read them in Arabic translations

So, the correct option is [4].