The right answer is d. Las
Definite articles are used to talk about specific nouns. In Spanish, there are four definite articles: el, la, los, and las and they often all translate to the same word in English: the. Nouns are often accompanied by articles. So the use of them points out the gender (either masculine or feminine) and number (either singular or plural) of a noun. In the Table below is shown the four forms that Spanish definite articles take. There are some exceptions to this rule. For example, if a feminine singular noun starts with a stressed a or ha sound then we use the masculine definite article rather than the feminine definite article.
Therefore:
Las muchachas colombianas son bonitas (Colombian girls are pretty)
