Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Outcome | Date | Surface | Opponent | Score |
| --- | --- | --- | --- | --- |
| Runner-up | 5 February 2007 | Carpet (i) | Gabriela Navrátilová | Cara Black Liezel Huber |
| Runner-up | 3 March 2007 | Hard | Ágnes Szávay | Martina Hingis Maria Kirilenko |
| Winner | 23 April 2007 | Clay | Ágnes Szávay | Martina Müller Gabriela Navrátilová |
| Runner-up | 23 July 2007 | Clay | Ágnes Szávay | Lucie Hradecká Renata Voráčová |
| Runner-up | 10 February 2008 | Hard | Eva Hrdinová | Alona Bondarenko Kateryna Bondarenko |
| Winner | 13 April 2008 | Clay | Bethanie Mattek-Sands | Victoria Azarenka Elena Vesnina |
| Runner-up | 27 July 2008 | Hard | Eva Hrdinová | Chan Yung-jan Chuang Chia-jung |
| Winner | 25 July 2009 | Hard | Julia Görges | Camille Pin Klára Zakopalová |
| Runner-up | 25 October 2009 | Hard | Renata Voráčová | Iveta Benešová Barbora Záhlavová-Strýcová |
| Winner | 24 July 2010 | Hard | Maria Kondratieva | Anna Chakvetadze Marina Erakovic |
| Runner-up | 31 July 2010 | Hard | Maria Kondratieva | Eleni Daniilidou Jasmin Wöhr |
| Runner-up | 26 September 2010 | Hard | Natalie Grandin | Julia Görges Polona Hercog |
| Runner-up | 25 April 2011 | Clay | Natalie Grandin | Iveta Benešová Barbora Záhlavová-Strýcová |
| Runner-up | 21 May 2011 | Clay | Natalie Grandin | Akgul Amanmuradova Chuang Chia-jung |
| Runner-up | 10 July 2011 | Clay | Natalie Grandin | Anabel Medina Garrigues Alicja Rosolska |
| Runner-up | 21 August 2011 | Hard | Natalie Grandin | Vania King Yaroslava Shvedova |
| Winner | 25 September 2011 | Hard | Natalie Grandin | Vera Dushevina Galina Voskoboeva |
| Runner-up | 26 May 2012 | Clay | Natalie Grandin | Olga Govortsova Klaudia Jans-Ignacik |
Question:
What was the surface of the match against bethanie mattek-sands?
Answer:
Clay