Final answer:
The phrase 'a lamb to the slaughter' means being innocent and defenseless. August's dad says this phrase because he's concerned about August's vulnerability.
Step-by-step explanation:
The phrase 'a lamb to the slaughter' means being innocent and defenseless. August's dad says this phrase because he's concerned about August's vulnerability. It is a metaphor that suggests that August is a gentle and harmless person who may face harm or danger due to his innocence and vulnerability.