We can use the reactivity series of metals to solve this.
The reactivity series of metals are (in descending order) : Potassium, sodium, Lithium, calcium, Magnesium, aluminum, zinc, iron, tin, lead, copper, mercury, silver, platinum, gold.
Since Potassium is the most reactive, the reaction with water should produce extremely violent gas.
Sodium is the next most reactive, so it should produce violent gas.
And Lithium is the least reactive out of the 3 metals, so it should be strong gas formation.
In addition, the gas produced should be hydrogen, since the reaction of metals should water should produce "metal name" hydroxide + hydrogen.
If they have 3 chemistry classes with 24 students, than there are 72 students in total. Each student requires 4 test tubes. 72 * 4 = 288 test tubes. Our answer is C.) 288 test tubes
