Final answer:
Robbie shows up at Sierra's window and leaves her alone when the corpuscules appear because he is concerned about saving himself. Robbie's tattoo represents Haiti and Sierra is surprised because she didn't know about his Taíno connection.
Option (c) is the correct answer.
Step-by-step explanation:
1. In the book 'Shadowshaper' by Daniel José Older, a character named Robbie shows up at Sierra's window.
2. Robbie leaves Sierra alone when the corpuscules appear because he is only concerned about saving himself. Option (b) is the correct answer.
3. Robbie's tattoo represents Haiti. Option (c) is the correct answer.
4. The Taíno were the indigenous people of the Caribbean. Sierra is surprised that Robbie has a Taíno tattoo because she was unaware of his connection to the Taíno culture.