Final answer:
Marty and Samantha find both Oscar Holden's album and Keiko's sketchbook, which Henry recognizes.
Step-by-step explanation:
In the context of the question, Marty and Samantha find items that Henry recognizes as significant. The correct answer to what they find is d. Both b and c, which are Oscar Holden's album and Keiko's sketchbook.
These items are critical in the story because they serve as a physical connection to the past and help in revealing more about the characters' histories and the emotional ties that bind them.