They had helped us a lot and we just tried to return their benevolence. (it Complex)

• ক Since they had helped us a lot, we just tried to return their benevolence. ✅ সঠিক উত্তর
• খ We just tri to return their benevolence, for they had helped us a lot.
• গ When they helped us a lot, we just tried to return their benevolence.
• ঘ If they had helped us a lot, we just tried to return their benevolence.