Concept:
This question tests reading comprehension, logical deduction, and cause-and-effect relationships. To determine the correct answer, we must first assess whether the statements are factually true on their own, and then determine if there is a direct logical connection linking the cause (Reason) to the effect (Assertion).
Step 1: Evaluate the validity of Assertion [As].
The assertion states that it was impossible to delay or "linger on the expedition." This describes an explicit constraint or limitation on time during a journey, implying that lingering would introduce danger. This statement functions as a true situational premise in coastal expeditions.
Step 2: Evaluate the validity of Reason [R].
The reason mentions that when a tide changes direction, it rushes in with immense speed, which can completely submerge low-lying areas and trap travelers by blocking their escape route back to safety. This is a well-documented physical hazard of coastal geography, making the statement factually true.
Step 3: Analyze the logical link between [As] and [R].
Let us link the two statements using the explanatory conjunction 'because':
\[
\text{"It was not possible to linger on the expedition \textbf{because} once the tide turned, }
\]
it came in rapidly and could cut off the return path."
The sentence flows logically. The high risk of being cut off by a fast-moving tide perfectly explains why travelers could not afford to waste time or linger. Therefore, both statements are true, and the reason serves as a clear, valid explanation for the assertion. This corresponds to option (A).