Select the synonym that best matches the phrasal meaning to alight (in the sense of getting down from a vehicle).

Introduction / Context:
This vocabulary question tests your understanding of phrasal verbs and their synonyms. The word to alight, in the context of travel, means to get down from a bus, train, or other vehicle. Many competitive exams ask you to select a word that closely matches such meanings, so it is important to know which verbs are commonly used in connection with passengers and vehicles.

Given Data / Assumptions:
- The phrase to alight is used here in the sense of getting down from a vehicle.
- Options: to escalate, to clamber, to disembark, to astride, to ascend.
- Only one of these is a standard verb for getting off a boat, bus, train, or aircraft.

Concept / Approach:
The verb disembark is commonly used to mean get off a ship, aircraft, or other vehicle. It is a formal equivalent of get down or get off. The other options have different meanings: escalate relates to increase or intensify, clamber describes climbing with difficulty, astride refers to sitting or standing with a leg on each side, and ascend means to go up. Therefore, the only word that correctly matches alight in this transport context is disembark.

Step-by-Step Solution:
Step 1: Focus on the specific meaning of alight intended here, which is getting down from a vehicle, not catching fire or shining.
Step 2: Recall which verb among the options is used in formal English to mean get off a means of transport.
Step 3: Identify disembark as the standard term for passengers leaving a ship, aircraft, or other vehicle.
Step 4: Eliminate verbs that describe climbing up, increasing, or sitting astride something rather than getting down.

Verification / Alternative check:
Consider an example: Passengers are requested to alight at the next stop. We can rewrite this as Passengers are requested to disembark at the next stop, which keeps the same meaning. Using escalate, clamber, astride, or ascend in this sentence would produce nonsense or a very different meaning. Standard dictionaries confirm that disembark means leave a ship, aircraft, or other vehicle, and is therefore the closest synonym to alight in this sense.

Why Other Options Are Wrong:
- to escalate: means to increase or intensify a situation, for example, a conflict can escalate; it has nothing to do with movement from a vehicle.
- to clamber: describes climbing or moving with difficulty using both hands and feet, usually up or over something, not simply getting off a bus or train.
- to astride: refers to positioning oneself with a leg on each side of something, as when sitting on a horse or rail; it is not about getting down from a vehicle.
- to ascend: means to go up or rise, which is the opposite direction of getting down from a vehicle.

Common Pitfalls:
Some learners confuse alight with words that involve climbing or mounting because they associate journeys with both boarding and leaving. The key is to focus on down versus up. To alight in this context is close to get off or get down, so you should look for a verb that clearly expresses downward or outward movement from a vehicle. Disembark is a useful formal synonym to remember for ships and aircraft, and it often appears in exam passages about travel or tourism.

Final Answer:
The best synonym for to alight in this context is to disembark.