Both stepped figures hide a word written out of order. Instead of testing every option blindly, we can guess the hidden word from its meaning first and then check that its letters match the figure.
The question tells us the two hidden words are synonyms of each other, so think of a well known pair of eight letter synonyms. IMMODEST and INDECENT fit well, since both describe behaviour or clothing that breaks accepted standards of propriety.
Left figure (letters T, I, M, E, D, O): IMMODEST is spelled I, M, M, O, D, E, S, T. Removing the letters T, I, M, E, D, O that the figure already shows leaves M and S as the two missing letters. This fits perfectly, since the figure has one M, one I, one O, one D, one E and one T already, and the word needs a second M and an S.
Right figure (letters T, I, N, E, C, E): INDECENT is spelled I, N, D, E, C, E, N, T. Removing the letters T, I, N, E, C, E that the figure already shows, which already accounts for both E's, leaves D and N as the two missing letters. This fits perfectly, since the word needs an extra D and a second N.
So the missing pair for the left figure is MS and for the right figure is DN, spelling IMMODEST and INDECENT, a genuine pair of synonyms.
Let's summarize:
Left figure blank: M and S, completing IMMODEST.
Right figure blank: D and N, completing INDECENT.
IMMODEST and INDECENT are synonyms, both meaning improper or lacking decency.
