Read and choose the correct definite article according to the number and gender of the noun that follows.
usted tiene clases de ciencias en la tarde.
los
la
las
el

Usted tiene LAS clases de ciencias en la tarde.

Explanation:

The noun clase in Spanish means class in English. It is feminine, so the article coming before it is: LA.

la clase

(or una clase if it is undetermined)

To make it plural, we add an -s to the noun and also to the article.

clase + s = clases

la + s = las

las clases

In this example, we have the determined article before the noun clases because it is a determined kind of class: clases de ciencias (science classes).

LAS

Explanation: