Step 1: Understanding the sentence.
The sentence describes the extent of the tourists' injuries. The word required should fit the context of severity. "Gravely" means seriously or severely, which is suitable for describing the seriousness of injuries.
Step 2: Analyzing other options.
- Spuriously means falsely or in a deceptive manner, which doesn’t fit the context.
- Fatefully refers to something that happens with great consequence, which doesn't align with the injury context.
- Vitally refers to something essential or necessary, which does not make sense in this context.
Step 3: Conclusion.
The correct word is "gravely" as it describes severe injuries.
Thus, the correct answer is 2. gravely.
Final Answer:
\[
\boxed{\text{The correct answer is 2. gravely.}}
\]