Which of the following are continuous functions?

Which of the following are continuous functions? (Select all that apply.)

(a)The temperature at a specific location as a function of time.

(b)The temperature at a specific time as a function of the distance due west from New York City.

(c)The altitude above sea level as a function of the distance due west from New York City.

(d)The cost of a taxi ride as a function of the distance traveled.

(e)The current in the circuit for the lights in a room as a function of time.

(f)None of these.

i don't understand how to interprete the wording