Let the x-axis represents the time and the y-axis represents the number of people infected.
As given in the question the number of people getting infected is increasing with time so N'(t) > 0
Now, it is also given that the rate of increasing of the infected persons is becoming slower with time that means as time increases the value of N'(t) is decreasing so N''(t) < 0
Hence the answer will be N'(t) > 0 and N''(t) < 0
That is option B.