Final answer:
Sarah Smarsh's brother mentioned in 'Heartland' is named Matt, and he is her younger sibling.
Step-by-step explanation:
In Heartland, Sarah Smarsh talks about her family and personal experiences to shed light on issues of poverty and social class in America's heartland. When referring to her brother in the book, his name is Matt, and he is younger than her. Therefore, the correct answer to the question is option b) His name is Matt, and he is younger than her.