Step 1: Sentence Comprehension.
The sentence indicates the seriousness of the tourists' injuries. The word needed should reflect the degree of harm. "Gravely" signifies seriousness or severity, accurately describing the condition of the injuries.
Step 2: Option Analysis.
- "Spuriously" implies falsity or deception, unsuitable for this context.
- "Fatefully" suggests an outcome with significant consequences, irrelevant to injury description.
- "Vitally" denotes importance or necessity, which is nonsensical here.
Step 3: Determination. "Gravely" is the appropriate word due to its meaning of severe injuries.Therefore, the correct choice is 2. gravely.
Final Answer: \[\boxed{\text{The correct answer is 2. gravely.}}\]