Step 1: Identify the pronoun.
The word “they” is a pronoun that refers back to a previously mentioned noun (its antecedent).
Step 2: Examine the sentence for possible antecedents.
Sentence:
\[
\text{“I asked at several shops for strawberries and the owners all told me they are out of season.”}
\]
Possible nouns:
shops
strawberries
owners
season
Step 3: Use meaning and logic.
The phrase “are out of season” logically applies to strawberries, not to shops, owners, or season itself.
Step 4: Identify the correct reference.
Thus, “they” refers to strawberries.
Hence, the correct answer is
\[
\boxed{\text{Strawberries}}
\]