Explanation:

Logic used is:

In this code language, words are represented with numbers formed by two parts.

The first component appears to be the length of the word.

'SPACE' has 5 letters, so it starts with 5. The rest is sum of reverse position of each letter i.e. 8+11+26+24+22=91

'ROTTEN' has 6 letters, so it begins with 6. The number '70' is derived in a similar manner.

For 'MEAN', it has 4 letters, so it begins with 4.

and sum of reverse position=14+22+26+13=75

So option 1 ( 4-75) is correct answer