Final answer:
Total probability sums up to 1. Since Roberto's probability of winning is 1/3, the probability of him not winning is 2/3, hence the total probability combined is 1.
Step-by-step explanation:
The total probability of an event encompasses all possible outcomes, and it sums up to 1. If Roberto has a probability of winning that is 1/3, it means there is a 2/3 chance of Roberto not winning.
Hence, the total probability, which includes both winning and not winning, is 1 (since 1/3 for winning + 2/3 for not winning equals 1). So, the correct answer to the question is c) 2/3, which represents the probability of Roberto not winning.