Question:
Who was the head coach of the team FC Viktoria Plzeň in Mar, 2020?

Context:
 Michal Bílek is the head coach of FC Viktoria Plzeň from May, 2021 to Dec, 2022. 
 Adrián Guľa is the head coach of FC Viktoria Plzeň from Jan, 2020 to May, 2021. 
 Pavel Vrba is the head coach of FC Viktoria Plzeň from Jul, 2017 to Dec, 2019.

Answer:
Adrián Guľa