In a graph of acceleration versus net force, the slope of the graph represents the inverse of the mass of the boat. This is based on Newton's second law of motion, which states that \( F = ma \) (force equals mass times acceleration). Rearranging this gives \( a = \frac{F}{m} \), indicating that acceleration (a) is directly proportional to net force (F) and inversely proportional to mass (m). Therefore, the slope of the graph (which is rise over run or \( \frac{a}{F} \)) reflects the inverse of the mass of the boat.
So, the correct response is: the inverse of the mass of the boat.