Answer:
Nadien is the answer for the blank
The ones with la are feminine and the ones with el are masculine. When the noun ends in an “a” it’s obviously feminine and when a noun ends in “el” it’s obviously masculine. It’s hard to tell whether it’s masculine or feminine when theres los and las and when it doesn’t end in an “a” or “e”
Camine dos cuadras y tome un autobús
Siga derecho hacia el hotel y busque un restaurante
I hope this helps, good luck!