Which symptom did Malcolm describe that MOST likely led the vet to zero in on this diagnosis?

Malcolm brings his dog to the veterinarian because she just isn’t acting like herself. When the vet asks Malcolm to explain, he says that she only plays with soft toys now instead of her rubber ball, she is losing hair in patches, she isn’t waiting for him at the door when he comes home from school, and sometimes she whines in her sleep. The veterinarian says that it is important to examine Malcolm’s dog and run some tests, but there may be a chance that she has hypothyroidism. Which symptom did Malcolm describe that MOST likely led the vet to zero in on this diagnosis?

She’s losing hair in patches.

She only wants to play with soft toys.

She doesn’t wait for him to get home.

She’s whining in her sleep.