Which word's spelling is the result of euphony?

Euphony refers to the harmonious and pleasing sound quality of words or phrases, often achieved through the arrangement of sounds and syllables. In the case of the word "addition," its spelling and structure contribute to a smooth auditory experience. The combination of consonants and vowels in "addition" flows easily when spoken, allowing for a more pleasant sound, which aligns with the concept of euphony.

On the other hand, the other words do not exemplify euphony in the same way. "Mystic" has a more abrupt sound due to the sharp consonant at the beginning and lacks the fluidity present in "addition." "Capture" includes a harder sound created by the consonant cluster, making it less melodic. "Photosynthesis," while interesting, has a complex structure that does not lend itself to a harmonious flow compared to "addition." Thus, "addition" best represents a word where its spelling results in euphony.