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For the scenario below, indicate the single most correct answer and why. 2. Road vehicle accidents involving ambulances have more detrimental outcomes than accidents involving other similarly sized vehicles (Ray and Kupas, 2005). Measures to avoid such accidents are continually being refined by organizations involved in emergency medical services. Suppose that a city council is interested in knowing if adoption of such measures has lead to an improvement over the last decade. Suppose that the ratio between the number of accidents involving ambulances (the numerator) and the number of kilometers driven by ambulances (the denominator) has been recorded (rt with units number of accidents per kilometer year) for each year t over the past decade. Which single one of the following statistical quantities is most relevant for investigating whether or not measures are leading to improvements? A) The sample standard deviation of It. B) The sample mean of It. C) The Pearson correlation coefficient p between rt and t. D) The regression coefficient for t in a linear regression with rt as the response variable and t as the explanatory variable. E) The regression coefficient for rt in a linear regression with r as the explanatory variable and t as the response variable