Which one of the following is correct ?
In terms of energy units, the correct order is: $1 ext{ cal} > 1 ext{ joule} > 1 ext{ erg}$. Specifically, $1 ext{ cal} = 4.184 ext{ joules}$ and $1 ext{ joule} = 10^7 ext{ ergs}$. Therefore, $1 ext{ cal} > 1 ext{ joule} > 1 ext{ erg}$.