The problem was so tough that he could not find out a solution. (it Affirmative)

• ক The problem was too tough for him to find out a solution. ✅ সঠিক উত্তর
• খ The problem was so tough for him to find out a solution.
• গ The problem is too tough to find out a solution.
• ঘ The problem is very tough to find out a solution.