B. Daisy's mum didn't want to have a pet because

Daisy's mum said that rabbits like jumping and their house is small. She also said that hamsters need a cage and they don't have time to take care of one. Therefore, the mum didn't want to have a pet because their house wasn't big enough for a jumping pet and they couldn't get a cage for a hamster.
1) their house wasn't big.