A physicist is measuring the mass of a certain radioactive substance several times during an experiment. Suppose this mass (in grams) after x minutes can be modeled with an exponential function. The graph of this function is shown below. Use the model to answer the parts to the right. (a) What is the initial mass of the substance? I] g X 53 The initial mass is represented by the \"Choose one) V l of the graph. (b) For the first 20 minutes, as time increases, the mass l(Choose one) V l. Mass (c) Give the equation of the asymptote. y : I] (g) Choose the statement that best describes the meaning of the asymptote. The mass of the substance does not fall below 0 g. The mass of the substance does not rise above 500 g. Time (minutes) The mass is measured for no more than 40 minutes