According to the 'Input Hypothesis' by Stephen Krashen, what is the ideal level of input for language acquisition?

1. ক
   Input that is far beyond the learner's current level
   
2. খ
   Input that is exactly at the learner's current level
   
3. গ
   Input that is slightly above the learner's current competence (i+1)
   
4. ঘ
   Input that is simplified to the level of a toddler