An automobile engine transforms chemical energy into mechanical energy.
Automobile engines have a range where they are most efficient.
Engines transform chemical energy into mechanical energy and have a range where they are efficient  .
The efficiency of an engine range is due to what?
Options:
[a] Movement of an air mass
[b] principals of aerodynamics
[c] transportation technology
[d] heat production
[e] heat is produced
[f] A transportation fuel
[g] Inches or fractions of inches.
[h] chemical to mechanical energy