Which one is a 'conversion' of a simple sentence into complex?

একটি Complex Sentence-এ একটি Principal clause এবং এক বা একাধিক Sub-ordinate clause থাকে।
অপশনগুলো বিশ্লেষণ:
- 'To his eternal disgrace, he betrayed his country' - এটি Simple Sentence।
- 'He must work very hard and make up for the lost time' - এটি Compound Sentence (and যুক্ত)।
- 'We must eat, or we cannot live' - এটি Compound Sentence (or যুক্ত)।
- 'He confessed that he was guilty' - এটি একটি Complex Sentence। এখানে 'He confessed' হলো Principal clause এবং 'that he was guilty' হলো Sub-ordinate clause। এটি মূলত 'He confessed his guilt' নামক Simple sentence-এর Complex রূপ।