Final answer:
The most likely gift that sparked the scientist's interest in geology could have been a rock collection, a set of geologist tools, a notable geology book, or an educational trip to a geological site.
Step-by-step explanation:
The gift that most likely sparked the scientist's interest in geology was something related to the study of Earth's physical structure and substance, its history, and the processes that act on it. Given the context of enjoying outdoor activities, it's probable that the gift was either a rock collection, a set of geologist tools, a geology book, perhaps Charles Lyell's Principles of Geology, or an educational trip to a site of geological significance, like a national park or a natural museum.