Respuesta :
The answer should be all of the above, considering The spelling rule is: if the word has 1 syllable (a word with one vowel sound), 1 vowel and it ends in 1 consonant, you double the final consonant before you add 'ing', 'ed', 'er',
The suffixes -ed, -er, and -ing can be added to the end of the word shop.
For which of the following do you need to double the final consonant before adding the suffix?
shop + -ing
shop + -ed
all of the above <----- The answer is all of the above.
shop + -er