According to Vygotsky’s sociocultural theory, what is the 'Zone of Proximal Development' (ZPD) in language acquisition?

1. ক
   The distance between what a learner can do alone and what they can do with guidance
   
2. খ
   The biological age at which language acquisition stops
   
3. গ
   The specific vocabulary learned in the first year of life
   
4. ঘ
   The innate ability to distinguish phonemes