Part A
The accurate statement based on the events of "Saving Tobe" is:
Tobe's near drowning causes Serafin to relive Valerio's death.
Part B
The evidence from the text that best supports the answer to Part A is:
"He was there, all over again, four years ago, looking into Valerio’s white, stone face as he lay dripping in the bottom of the boat."
This quote directly indicates that Serafin is reminded of a traumatic past experience involving Valerio when faced with Tobe's near drowning.