In the following sentence, one part contains a grammatical error. Identify the part that has the error. If the sentence is free from error, select No error. Their luggages which were(A) / kept in the station(B) / restroom lockers, were later retrieved.(C) / No error(D)

Introduction / Context:
This is an error spotting question that tests your understanding of countable and uncountable nouns and subject verb agreement. The sentence describes luggage kept in station restroom lockers. You must identify which labelled part of the sentence contains the grammatical error.

Given Data / Assumptions:
Full sentence: Their luggages which were(A) / kept in the station(B) / restroom lockers, were later retrieved.(C) / No error(D).
Part A: Their luggages which were.
Part B: kept in the station.
Part C: restroom lockers, were later retrieved.
Part D: No error, which is chosen only if A, B and C are all correct.
Assume standard modern English usage for exams.

Concept / Approach:
The noun luggage is an uncountable noun in standard English. It does not normally take a plural form luggages and is followed by a singular verb when treated as a collective item. For example, we say Her luggage was lost, not Her luggages were lost. The approach is to look for misuse of plural with uncountable nouns or subject verb disagreement.

Step-by-Step Solution:
Step 1: Examine part A: Their luggages which were. The word luggages is incorrect because luggage is normally uncountable and does not take a plural form in this context. Step 2: A correct version would be Their luggage, which was, using the singular form and appropriate verb. Step 3: Examine part B: kept in the station. This is fine and simply indicates location. Step 4: Examine part C: restroom lockers, were later retrieved. This part correctly states where the luggage was stored and that it was later retrieved, though the plural verb were comes from the earlier plural form, which was already wrong. Step 5: Since the main and clearest error arises in part A, that is the part we must mark. Step 6: Therefore, option A is the correct choice for the part containing the error.

Verification / Alternative check:
Rewrite the entire sentence correctly: Their luggage, which was kept in the station restroom lockers, was later retrieved. In this form, the sentence is grammatical and natural. Comparing this with the original highlights that luggages and which were were the problems, both tied to part A.

Why Other Options Are Wrong:
Option B, kept in the station, is grammatically correct and simply describes place.
Option C, restroom lockers, were later retrieved, would be acceptable once the subject luggage is corrected to singular and the verb adjusted, so the structure itself is not the primary issue being tested.
Option D, No error, would be chosen only if all three parts were correct, which is not the case.

Common Pitfalls:
Many learners are tempted to pluralise luggage because it refers to multiple bags, but in standard English luggage, baggage, furniture and equipment are uncountable. Another pitfall is to focus only on obvious spelling mistakes and miss countability errors, which examinations often test directly.

Final Answer:
The erroneous part of the sentence is Option A, which contains the incorrect plural form luggages.