To find the 19th word in the dictionary order of all permutations of the letters in the word "MASK," we need to arrange the letters in alphabetical order and determine the word at the 19th position.
The alphabetical order of the permutations is as follows:
AKMS
AMSK
KAMS
KASM
KSAM
KSMA
MAKR
MARK
MASK
MKAS
MKSA
MSKA
MSKA
SAMK
SAKM
SKAM
SKMA
SMKA
Therefore, the 19th word in alphabetical order is "SAMK" (option C).