Hint: Exponential growth is a form of growth of population where unlimited resources are present. When organisms go through exponential growth, the curve made by them is J-shaped or exponential. In the case of this question, if the growth can be measured in terms of hours, it should be easy enough.
Let’s discuss the question and find the proper answer.
In the given question, the growth rate of the leaf is 0.015 $mm^2$ per hour
Here we have to calculate the range of growth for 4 days.
As we know, One day is equal to 24 hours, so 4 days will be 96 hours.
Now for calculating the growth of the area of the leaf, we have to multiply 0.015 with 96.
Hence, after 4 days, the total growth will be = 1.44$mm^2$
Therefore, after 4 days, the leaf area will be= (10+1.44) $mm^2$ i.e. 11.44 $mm^2$
Hence option A: 10-12$mm^2$ is the correct answer.
Note: There are mainly two types of growth of the population that are noticed. One is exponential or J-shaped that is discussed above and another one is the logistic growth curve or sigmoidal growth curve that is S-shaped. The sigmoidal growth curve has three phases including the lag phase, log phase, and stationary phase.