3. (b) It is not clear on the facts whether A is likely to be liable. Apart from Queensland, all the Australian states and territories have statutes governing the liability of dog-owners and persons in control of dogs.
In some jurisdictions it is necessary to prove that the owner knew the particular animal might cause injury. In other jurisdictions (for example NSW and the Northern territory) liability is strict and such knowledge is not necessary.
Some jurisdictions provide for specific defences (for example that the defendant was injured while unlawfully on the defendant's premises, or failed to take reasonable care). In other jurisdictions similar defences are available by implication. So, to determine if A would be liable would require finding and carefully reading the relevant legislation.