Which one is the simple sentence?

অপশনগুলোর মধ্যে What is lotted cannot be blotted হচ্ছে একটি simple sentence. বাকি অপশনগুলো Complex sentence.
Simple sentence:
- এসব বাক্যে একটি subject থাকে এবং একটি finite verb বা সমাপিকা ক্রিয়া থাকে।
• Example:
- Bangladesh is a populated country.
- Human is the superior in this planet.
- What is lotted cannot be blotted.
- He heard me singing.
•এসকল বাক্যে subject + finite verb + complement বসে।

Complex Sentence:
- একটি principal Clause থাকে।
- এক বা একাধিক subordinate clause থাকে।
- subordinate clause শুরু হয় - who, which, that, when, how, where, while, if, because, since, as, though, although, till, unless, before, so that,as soon as etc.
• Example:
- I do not know what his name is.
- while there is life there is hope.
- A dog does not bite unless it is teased.
- If you read, you will pass.

Source: A passage to the English language, S.M. Zakir Hussain.