Final answer:
Sentence (a) '...students often struggle to find the resources they need to succeed in school.' is the one that best supports the reason on the note cards about students facing challenges in finding academic resources.
Step-by-step explanation:
When determining which sentence from the source best supports the reason stated on the note cards, it is important to align the information provided with the context of the note cards. If the note cards pertain to the challenges students face in locating resources to be successful in academic work, then sentence (a) '...students often struggle to find the resources they need to succeed in school.' is the source best supports the topic. This sentence directly addresses the difficulty of finding reliable and useful resources for schoolwork, which aligns with the notion of students requiring support for academic success that is implied on the note cards.