Which of the Following Accounts for Slower Modulation Frequencies in Truck

Multiple Choice

Which of the following accounts for slower modulation frequencies in truck pneumatic brake systems than equivalent hydraulic brake systems?

A) trucks move more slowly than automobiles
B) compressibility of air versus that of hydraulic fluid slows switching frequency
C) truck chassis computers function at slower clock speeds than automobile computers
D) truck ABS system have to manage many more brakes than automobile ABS