Question:
Which position did Chang San-cheng hold in Apr, 2016?

Context:
 Chang San-cheng holds the position of Mayor of Taoyuan from Dec, 2022 to Dec, 2022. 
 Chang San-cheng holds the position of President of the Executive Yuan from Feb, 2016 to May, 2016. 
 Chang San-cheng holds the position of Vice Premier of the Republic of China from Dec, 2014 to Jan, 2016.

Answer:
President of the Executive Yuan