Choose the word which does not have the same suffix as the remaining three -

Correct option is C

A suffix is a group of letters added at the end of a word to modify its meaning. The words harm, colour, and thank can take the suffix "-ful" to form harmful, colourful, and thankful, respectively. However, noise does not commonly take the suffix "-ful" (the word "noiseful" is rarely used). Instead, the commonly used form is "noisy", which takes the "-y" suffix instead of "-ful".
Thus, "noise" is the odd one out as it does not follow the same "-ful" suffix pattern as the others.