Final answer:
option C. Mary's first son's name suggests that she did not have a strong grasp of the Seneca language.
Step-by-step explanation:
Based on the information provided, we can infer that Mary's first son's name indicates that she did not have a strong grasp of the Seneca language. The passage mentions that Caitlin had studied Spanish in school for years but was not prepared for the language and customs she encountered. Therefore, we can conclude that Mary, who is mentioned in a different context, also faced a language barrier and did not have a strong command of the Seneca language.