D Question 19 0.5 pts In the difference equation, Rt+1 = Rt + ylt, what does the term yl represent? The fraction of the population that is recovered from the infectious disease in time step t, where y is the removal rate. The population that is recovered from the infectious disease in time step t, where y is the removal rate. The population that is recovered from the infectious disease in time step t, where y is the transmission coefficient. O The population that is becoming infected with the infectious disease in time step t, where y is the removal rate. D Question 20 0.5 pts In the standard SIR model, Rt is the fraction of the population that is recovered from the disease. O True O False D Question 21 0.5 pts In the standard SIR model, the coefficient " is the transmission coefficient, which is the probability that a susceptible individual who comes into contact with an infected individual will become infected. True O False