Answer: D) firm / Room
Slant rhyme, more commonly known as half-rhyme, is a poetic device used to give an "inharmonious feeling in a rhyme scheme". Slant rhyme describes words whose stressed ending consonants match, but the proceeding vowel sounds don't match.
Answer D is the only one who consonants' sounds match; the 'm' sound being stressed on both words. The "ir" and "oo" do not sound the same though, so it is a slant rhyme.
