Final answer:
b. Don Giovanni is seducing Zerlina. In Mozart's opera Don Giovanni, the duet "Là ci darem la mano" is sung when Don Giovanni is seducing Zerlina.
Step-by-step explanation:
In Wolfgang Amadeus Mozart's opera Don Giovanni, the duet "Là ci darem la mano" is sung between the characters Don Giovanni and Zerlina when Don Giovanni is seducing Zerlina. This duet takes place in Act I of the opera. Don Giovanni uses his charm and persuasive skills to try and win over Zerlina, who is engaged to another character, Masetto. The duet showcases Don Giovanni's seductive nature and Zerlina's temptation.