What reference source supplies information about the etymology of a word ?

Fill the blank with a la, a las, a los, or al. mi padre .

Question 10 (fill-in-the-blank worth 1 points) susana cruza la calle en el paso de answer for blank 1:

Which one of the following is the correct rhyme to keep in mind when using the spanish counterparts to this, that, those and these? a: “that” and “those” both have s’s, “this” and “these” don’t b: “that” and “those” both have t’s, “this” and “these” don’t c: “this” and “these” both have s’s, “that” and “those” don’t d: “this” and “these” both have t’s, “that” and “those” don’t