The frequency of cars entering the parking lot is a discrete variable so option (d) will be correct.
What is a variable?
A variable in mathematics is a representation of any quantity whose value is changeable.
For example speed of a vehicle is a variable.
The value of the variable changes but the meaning of the variable never for example speed of vehicle changes but the word speed does not change.
A discrete variable is a variable whose values are different.
Since car color is not a variable because the meaning of variable is not constant in car color.
The frequency of vars is a discrete variable because it is different for each kind of car.
Hence "The frequency of cars entering the parking lot is a discrete variable".
To learn more about variables,
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