An intensive search was conducted by the detective to locate those criminals, who —.

✅ কেন সঠিক: The escape happened before the search (which is in the past), so the earlier past action takes the past perfect: who had escaped.

❌ অন্য অপশন: ‘have had escaped’ is not a correct form; ‘are escaping’ and ‘have been escaping’ do not fit a past narrative.

💡 মনে রাখুন: Two past actions: the earlier one in past perfect (had + V3), the later one in simple past.