What importance of opportunity cost to an firm​

Weighing opportunity costs allows the business to make the best possible decision. If, for instance, the company determines an alternative choice's opportunity cost is greater than what the company gains from its initial decision, the company can change its mind and pursue the alternative choice.

i'm not sure i completely understand your question, but i will do my best.

i think the answer you are looking for is sequence. (see below)

a repeated melodic fragment would be best defined as repetition, while repeated chords (different or the same) could be a chord progression. however, you then mentioned the chord and melodic fragment beginning on higher or lower pitches, in that case, the answer could be best defined as a sequence. the definition of a sequence is as follows: "the restatement of a motif or longer melodic (or harmonic) passage at a higher or lower pitch in the same voice."

let me know if this !

trying using google im so sorry