indefinite articles $10\nfill in the blank with the correct indefinite article. ______ lección\nun\nuna\nunas…

Brief Explanations:

In Spanish, "lección" is a feminine singular noun. The indefinite article for feminine singular nouns is "una". "un" is for masculine singular, "unas" for feminine plural, and "unos" for masculine plural. So the correct indefinite article for "lección" is "una".

Answer:

B. una (assuming the options are labeled with A. un, B. una, C. unas, D. unos; here the correct option is the one with "una" which is highlighted)