With reference to Upanishad in India consider the following statements:

1. Upanishad literally means ‘approaching and sitting near’ and the texts contain conversations between teachers and students. 

2. Most Upanishadic thinkers were men, especially brahmins and rajas. 

3. Poor people commonly took part in Upanishad discussions.

4. Many of the ideas of the Upanishads were later developed by the famous thinker Shankaracharya.

Which of the statements given above is/are correct?