Final answer:
Clytaemnestra sobbed by the torch she lit for her daughter, Iphigenia.
Step-by-step explanation:
In the play, Clytaemnestra says that she "sobbed by the torch I lit for" her daughter, Iphigenia. This statement refers to the events that took place before the play begins, when Clytaemnestra sacrificed her daughter to appease the gods and secure favorable winds for the Greek ships sailing to Troy. Clytaemnestra's grief and regret over her actions are expressed in this line.