“Potentially dangerous dog” means any of the following:

1. (a) Any dog which, when unprovoked, on two separate occasions within the prior 36-month period, engages in any behavior that requires a defensive action by any person to prevent bodily injury when the person and the dog are off the property of the owner or keeper of the dog.
2. (b) Any dog which, when unprovoked, bites a person causing a less severe injury than as defined in Section 31604.
3. (c) Any dog which, when unprovoked, on two separate occasions within the prior 36-month period, has killed, seriously bitten, inflicted injury, or otherwise caused injury attacking a domestic animal off the property of the owner or keeper of the dog.