Answer:
- Estoy buscando.
Step-by-step explanation:
In this task you have to complete the blank with the appropriate tense of the verb. In this case you have to use the present progressive tense. So the correct option here would be "estoy buscando".
The present progressive tense is formed with subject + verb "estar" + verb "-ando, -iendo". In this case the subject is the first person "yo" so the sentence must be completed as in the following example:
- Yo estoy buscando la maleta perdida.