A finance magazine conducted a year long study of investment strategie

Argument says The randomly selected Investment was more profitable at the end of the year while the investments selected by Experts were less profitable at the end of the year. So, it concluded its not worth spending money to hire those experts.

I would say it is the weakest argument.

May be what he selected was a Guess. Or May be what they selected is a Diamond over a long term and not a short term.

A. The financial planners selected for the study are regarded as some of the top experts in their field. : So, How does that relate to conclusion. IRRELEVANT.
B. Most financial planners select investment portfolios designed to mature over a long period of time. : Wow, as per my Pre Thinking. Correct
C. The randomly selected investment portfolio included some of the same investments chosen by the experts. : Some of the?? What about the others? What does Some of the means? Is it 1 or 2 or all? We don't know. Incorrect.
D. The magazine’s portfolio returns were only slightly higher than the returns of the financial planners.’: Still man, it was higher no matter how much. Strengthener.
E. Most investments decisions begin to pay off after one year. : But what these 5 Uncles/Aunts suggest Didn't, right? Irrelevant.

A finance magazine conducted a year long study of investment strategies. The magazine asked financial planners from five prestigious companies to each select a portfolio of investments, the return on which the magazine tracked over the year. Additionally, the magazine selected its own portfolio at random and tracked its return. At the end of the year, the random investment portfolio outperformed each of the expert’s investment picks. Thus, there is no benefit to hiring financial planners for help in investing.

Which of the following, if true, casts the most doubt on the validity of the conclusion drawn above?
A. The financial planners selected for the study are regarded as some of the top experts in their field.
B. Most financial planners select investment portfolios designed to mature over a long period of time.
C. The randomly selected investment portfolio included some of the same investments chosen by the experts.
D. The magazine’s portfolio returns were only slightly higher than the returns of the financial planners.’
E. Most investments decisions begin to pay off after one year.

I was able to eliminate a,c and d. I was confused with b and e. B- says investment portfolios designed to mature over a long period of time. I felt it was talking about maturity time. So, I thought of going for E option. Pls correct me?