As soon as he reached there, all the culprits fled away. (make it simple)

• ক On his reaching there, all the culprits fled away. ✅ সঠিক উত্তর
• খ At the time of his reaching there, all the culprits fled away.
• গ On reaching there, all the culprits fled away.
• ঘ In his reaching there, all the culprits fled away.