Final answer:
The momentum of a 45 kg Great Dane running at 13 m/s is calculated as 585 kg·m/s, which is option A.
Step-by-step explanation:
The momentum of an object can be calculated using the formula p = mv, where p is the momentum, m is the mass, and v is the velocity. In the case of a Great Dane with a mass of 45 kg running at a speed of 13 m/s, the momentum will be 45 kg × 13 m/s = 585 kg·m/s. Therefore, the momentum of the Great Dane is 585 kg·m/s, which corresponds to option A.