Answer:
The selection of the answers from the answer choices for all fill-in-the-blank will depend entirely on correct use of vocabulary and their correct meaning in Spanish. As such, here are the answers with their counterparts in English for better understanding of why the choice is one over the others.
1. Daniel quiere convertirse en astronauta pero es muy bajito (short). The other words in the options do not exist in Spanish.
2. No puedo econtrar el librillo (booklet) de instrucciones de mi teléfono inalámbrico. The other options are, spelling-wise, incorrect, and only librillo means small booklet, or simply booklet.
3. Necesitan una bombilla (light bulb) en el laboratorio para poder continuar con el experimento. Bombilla is the only correct word used to mean light bulb.
4. Vimos una estrella fugaz por la ventanilla (plane window) del avión. This is the only word for a small window on a plane.
5. Los astrónomos observaron unas lucecitas (small lights) en el cielo que parecían un ovni. Lucecitas is the diminutive word for simply lights, in English. In Spanish they are common when we want to talk about something small.