Question:
Who was the chair of Union, Progress and Democracy in Aug, 2011?

Context:
 Gorka Maneiro Labayen is the chair of Union, Progress and Democracy from Jan, 2016 to Jan, 2017. 
 Cristiano Brown is the chair of Union, Progress and Democracy from Jan, 2017 to Dec, 2020. 
 Rosa Díez is the chair of Union, Progress and Democracy from Sep, 2007 to Jul, 2015. 
 Andrés Herzog is the chair of Union, Progress and Democracy from Jul, 2015 to Jan, 2016.

Answer:
Rosa Díez