Question:
Who was the head coach of the team TSC Bačka Topola in Sep, 2021?

Context:
 Žarko Lazetić is the head coach of TSC Bačka Topola from Nov, 2021 to Dec, 2022. 
 Mladen Krstajić is the head coach of TSC Bačka Topola from Jan, 2021 to Oct, 2021. 
 Zoltan Sabo is the head coach of TSC Bačka Topola from Aug, 2018 to Dec, 2020.

Answer:
Mladen Krstajić