Final answer:
The correct indefinite article to accompany the noun 'mochilas' is 'Unas mochilas'.
Step-by-step explanation:
The correct indefinite article to accompany the noun 'mochilas' is Unas mochilas.
In Spanish, the use of indefinite articles depends on the gender and plurality of the noun. 'Mochilas' is a plural noun, so the correct indefinite article to use is 'Unas' for feminine, plural nouns.
For example, you could say 'Unas mochilas azules' which means 'Some blue backpacks'.
Learn more about Indefinite articles in Spanish