Directions: Select the most appropriate word to fill in the blank. The job of…

Concept: In a single-blank sentence-completion item, the blank occupies one syntactic-and-semantic slot: the chosen word must fit BOTH the grammatical structure of the sentence AND the meaning the rest of the sentence sets up, including which prepositions/phrases it standardly combines with (its collocation).

Application: The blank sits inside ‘those ________ for a fixed-hours work profile’, a reduced relative clause modifying ‘those’ (compare ‘those working for…’, ‘those applying for…’). This slot needs a present-participle verb form that can take ‘for + noun phrase’ as its complement, expressing an ongoing action directed toward that noun phrase. The sentence's overall sense is that a railway officer's job does not suit people who want a fixed-hours schedule (railway officers typically work irregular or shift duty). ‘Looking for’ is the standard verb-plus-preposition combination meaning ‘seeking’ or ‘searching for’ (as in ‘looking for a job’), and it supplies exactly this sense.

Cross-check: Each remaining option fails on its own terms:

• Astonishing/astonish is a transitive verb meaning ‘to amaze someone’; it does not combine with ‘for’ to mean an ongoing pursuit of something, so ‘astonishing for a fixed-hours work profile’ has no sensible reading. The word is normally used as a descriptive adjective (e.g., ‘an astonishing result’), not as an action ‘those’ are performing.

• Allotting/allot means to assign or distribute something to someone (e.g., ‘allotting duties’); it does not take ‘for’ in the sense of seeking, so it reverses the intended relationship rather than expressing it.

• Surprising/surprise, like astonish, is a transitive verb meaning to cause surprise in someone; it does not combine with ‘for’ to express seeking something, and is normally used adjectivally (e.g., ‘a surprising turn’), not as the action here.

• Learning/learn means to acquire knowledge or a skill (e.g., ‘learning a language’); ‘learning for a work profile’ is not a standard English collocation — one learns a skill or subject, not ‘for’ a schedule.

Looking is therefore the only option that both fits the required grammatical slot and carries the standard idiomatic meaning in context, making it the right choice.