The correct option is A chopped
Option B: 'Chopped' means 'to cut off (parts of the tree)'. It's the
most suitable word, as it completes the sentence in meaning: they picked up their axes and
'cut off' the thick thorny bushes. Hence
option B is correct.
Option A: 'Slice' means 'to cut something, generally food, into thin pieces', like a 'slice of bread'.
This word does not relate to the 'cutting off of bushes'. They cannot be sliced.
Option C: 'Pulled' means 'to move something in your way'.
Option D: 'Scratched' means 'to wound someone by marking them with a pointed object'.
These words do not relate to the cutting of thorny bushes. One cannot slice, pull or scratch with an axe.
Hence options A, C and D are incorrect.