If it is true that a company's performance is affected by many factors, one can conclude that A. two companies producing the same goods will perform equally well. B. a company's success is dependent on amateur investors. C. it is possible to lose money by investing in a company that has been very successful. D. an amateur stock investor will automatically make more money than a professional.

First, carefully read through each of the options provided and think about how they relate to the statement that "a company's performance is affected by many factors." A. two companies producing the same goods will perform equally well: This option assumes that if two companies produce the same goods, their performance will be the same. However, the statement tells us that many factors affect a company's performance, so it is possible that two companies producing the same goods have different performances due to other factors. B. a company's success is dependent on amateur investors: This option suggests that amateur investors play the most important role in a company's success. While amateur investors can certainly have an impact on a company's performance, the statement says that there are many factors involved, so we cannot conclude that a company's success is solely dependent on amateur investors. C. it is possible to lose money by investing in a company that has been very successful: This option acknowledges the possibility of losing money even if a company has had past success. Since a company's performance is affected by many factors, it is plausible that changes in those factors could lead to less success in the future and, as a result, a loss for investors. D. an amateur stock investor will automatically make more money than a professional: This option claims that amateur investors will always outperform professionals, but this is not a logical conclusion based on the statement about many factors affecting a company's performance.

After analyzing each option and their relationship to the statement, we can conclude that option C is the most plausible consequence. It states that it is possible to lose money by investing in a company that has been very successful, which is consistent with the notion that a company's performance is affected by many factors, and those factors could change over time, leading to a decline in success. Therefore, the correct answer is: C. it is possible to lose money by investing in a company that has been very successful.