Concept:In words with several syllables, one syllable is said with greater force.For “economic,” the third syllable receives the stress.Explanation:Pronounce the word slowly: e-co-NOM-ic.The syllable “NOM” sounds louder, longer, and clearer than the others.So the correct stress mark is placed on “NOM.”This matches the pattern ec-o-NOM-ic.Answer:Option C: ec-o-NOM-ic.