Answer:
Los cereales son mi comida preferida para el desayuno.
Translation:
<em>Cereals are my favorite breakfast food.</em>
Explanation:
The correct option here is <em>LOS</em>. <u>Articles in Spanish should always agree on number and gender with the noun</u>.<em> </em>
<em>Las</em> should only be used when the noun is plural and feminine; and <em>cereales</em> is plural and masculine. For this same reason, <em>unas</em> would also be a highly incorrect article for the noun.
<em>Unos</em>, however, agrees with both the number and the gender and the noun, but it doesn't sound as appropriate for this sentences as <em>Los</em> does.
