In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: What was the ranking of the player Rivas defeated in a tiebreak in the Parioli Challenge? Passage:During his professional career his ranking peaked at 116 in 1985, a year in which he made the round of 16 at the WCT Tournament of Champions in Forest Hills. One of his wins in that tournament was over 10th seed Tim Wilkison, then ranked 36th in the world. In 1985 he also had a win over Thomas Muster, en route to the final of the Parioli Challenger. In the final he saved two match points to defeat Simone Colombo in a last set tiebreak. It was the first of two Challenger tournaments that he won, the other was the 1988 Crans-Montana Challenger. In 1989 he made the quarter-finals of a Grand Prix tournament, the Rio de Janeiro Open, and beat Petr Korda at a Challenger event in Clermont-Ferrand.
 Links: a. Parioli Challenger b. Tim Wilkison c. Rio de Janeiro Open d. Simone Colombo
A: 
d