Under what condition does 'c' make the (s) sound?

The reason why 'c' makes the (s) sound before the letters e, i, and y is rooted in the rules of English phonetics and orthography. When 'c' is followed by these specific letters, the pronunciation shifts from the hard (k) sound to the softer (s) sound. For example, in words like "cell," "city," and "cylinder," the presence of e, i, or y prompts this pronunciation change. This phonetic rule provides a systematic way for learners to predict how 'c' will be pronounced in various contexts, enhancing their understanding of sound-letter relationships in English.

Other conditions presented in the options do not adhere to this consistent phonetic principle, making them less applicable in explaining the sound of 'c.'