Hey @Shashwat_Gupta and welcome to the DLS,
We can’t discuss right or wrong answers on the quiz here. That said, we can discuss general cases and bias and variance tradeoff. Please, check this post out. I believe you may find answers on your questions there.
Note that we use a train set for training only, dev and test sets for evaluation of our models.
The choice would depend on a particular case and our intention.
- We may add data to the train set to address variance on dev and test sets.
- We may add data to the dev set to address data mismatch in dev and test sets.