Question

¿dónde está mi bolígrafo?
en tu escritorio
en la ventana
en la puerta
en tu reloj

Explanation:

The question asks "Where is my pen?" in Spanish. We need to identify the logically plausible location for a pen. A desk (escritorio) is a common place to keep a pen, while a window, door, and watch are not typical locations for this item.

Answer:

en tu escritorio