Final answer:
The younger sister's husband can select a birthday gift for the older sister that is thoughtful and relevant to her interests, as the types of gifts mentioned in the reference text imply a range of options based on individual preference and the nature of the relationship.
Step-by-step explanation:
The younger sister's husband might choose to buy the older sister a gift that is meaningful and thoughtful for her birthday. A direct answer to what the gift could specifically be is not provided in the reference text. However, the excerpt mentions various presents given for a different occasion, which provides examples of gifts that can be chosen based on the recipient's interests and the giver's relationship with them. For instance, an ice-water set and a carving knife with elk-horn handles were given by Trina's parents, while a chatelaine watch of German silver was from Marcus Schouler, indicating that gifts may vary significantly depending on who is giving them and their intended purpose or significance.
Choosing a birthday present for a sibling's spouse requires consideration of the individual's preferences, your relationship with them, and possibly their relationship with other family members. Practicality, sentimentality, and personal interests often guide the selection process. If the older sister enjoys music, for example, a gift similar to a parlor melodeon might be appreciated, assuming it aligns with her interests.