Interaction Plots with R

Do I list TypeBeat as a factor or the type of beat (upper-class, middle-class, inter-city) as a factor to run an interaction graph? I am so confused.

Here is the data:

Type Beat 5 Hours 10 Hours 15 Hours
upper-class beat 34.4 35.5 39.2
middle-class beat 30.2 32.4 34.7
inner-city beat 20.1 39.4 54.3