The slope of a graph of acceleration versus net force represents the inverse of the mass of the boat. This relationship is described by Newton's second law of motion, which states that \( F = ma \) (force equals mass times acceleration). When rearranging this equation, acceleration \( a \) can be expressed as \( a = \frac{F}{m} \), indicating that the slope (which is \( \frac{a}{F} \)) is equal to \( \frac{1}{m} \). Thus, the correct response is:
the inverse of the mass of the boat.