How is the number nineteen expressed in Spanish?

The number nineteen is expressed in Spanish as "diecinueve." This term is formed by combining "diez" (ten) and "nueve" (nine), effectively translating to "ten and nine." In the Spanish language, numbers are often constructed using combinations of the words for the tens and the ones, and "diecinueve" is a prime example of this structure.

The other choices represent different numbers: "veinte" means twenty, "dieciséis" translates to sixteen, and "diecisiete" refers to seventeen. Each of these terms demonstrates how Spanish numbers are uniquely constructed, but they do not correspond to the number nineteen, confirming that "diecinueve" is the accurate term for that figure.