Final answer:
Based on the context of the passages provided, Mac is fervent in his remark, particularly in the intense and emotionally charged scenario where Marcus acknowledges Mac's deeper passion for Trina, thus deciding to step aside in affection for her.
Step-by-step explanation:
The student's question regarding Mac's comment in line 43 reveals that Mac is fervent in his remark. This is primarily due to the context provided by the narrative surrounding Mac. In Frank Norris's novel, we see a portrayal of Mac that suggests a deep emotional involvement, especially with respect to Trina. For example, Marcus acknowledges Mac's strong feelings for Trina and decides to step aside, allowing Mac to pursue her. This decision is catalyzed by Marcus's recognition of Mac's significant passion, even considering that Marcus himself is described as 'twice as clever.' It is important to note the intensity of the interactions between Marcus and Mac, as well as the drama infused in the moment Marcus gives up his claim on Trina for Mac, which showcases the fervor in the characters' actions and speech.