Explanation:

To translate "grey of" using the code given:

- ‘pinch of salt grey’ ? ‘ab tr # kp’

- Words: pinch, of, salt, grey

- Codes: ab, tr, #, kp

- ‘grey colour is black’ ? ‘# jm bk if’

- Words: grey, colour, is, black

- Codes: #, jm, bk, if

- ‘colour are of track’ ? ‘gt if ab fr’

- Words: colour, are, of, track

- Codes: gt, if, ab, fr

Shared words to codes:

- "grey" corresponds to ‘#’

- "of" corresponds to ‘ab’

Therefore, "grey of" would be written as ‘ab #’.

- Options:

- Option 1: ab if

- Option 2: gt fr

- Option 3: ab #

- Option 4: gt #

So, the correct option is 3: ab #.