What does the term 'Overregularization' refer to in child language development?

1. ক
   Using a word to cover a wider range of meanings than it should
   
2. খ
   Applying grammatical rules to irregular words, such as saying 'goed' instead of 'went'
   
3. গ
   The inability to pronounce certain consonants correctly
   
4. ঘ
   The process of repeating words heard from adults