Read passage and answer following question.
Students carry out an experiment to explore effect of different environments on blood flow using small, freshwater fish. Each fish is placed into a petri dish. A wet cotton ball is placed over its gills to allow for diffusion of oxygen, which will keep fish alive. The students n place petri dish onto stage of a light microscope so that thinnest part of tail is directly under objective lens and blood can be seen flowing in blood vessels. While focusing on a capillary, students count number of red blood cells flowing through vessel at 5-second intervals. After monitoring normal flow of blood for 30 seconds, environment in petri dish is altered in one of five different ways. Students observe and record change in blood flow if any. After experiment, each fish is returned to fish tank.

Experiment 1 - Nothing is added to this petri dish.
Experiment 2 - Water at a temperature of $5^{\circ }C$ is added.
Experiment 3 - Water at a temperature of ${30}^{\circ }C$ is added.
Experiment 4 - Ethyl alcohol is added.
Experiment 5 - Nicotine extracted from cigarette tobacco is added.

Experiment	Initial average rate of blood flow	Final average rate of blood flow
1	9	9
2	8	4
3	9	13
4	8	5
5	9	12

Which of following statement is incorrect about this experiment?