The mathematical problem was so tough that I could not find a solution. (Affirmative)

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