Independent concert promoters, in order to maintain their credibility

The answer is E in my view.

Premise: Independent concert promoters must represent the concert tours of well-known artists in order to maintain their credibility and compete with larger, publicly traded promoters.
Premise: These private companies (Independent concert promoters) have had to increase their guaranteed payments to famous clients (well-known artists) to attract such business.
Premise: Smaller promoters have raised their ticket prices, resulting in low attendance at a number of recent shows in order to offset these increases (guaranteed payments).

A. Independent concert promoters often lose money by representing well-known artists. This is not necessarily true per the information provided above. Independent concert promoters have had to increase their guaranteed payments to famous clients. In addition, they have raised their ticket prices resulting in low attendance. These actions could lead to loss of money or maybe not. Hence we can't infer A from the information provided above.

B. The largest independent concert promoter has fewer employees than the smallest publicly traded promoter. This is incorrect and entirely out of scope as far as the information provided above is concerned.

C. Ticket price is the most important determining factor for concert attendance. This is not necessarily true. Increased ticket prices have resulted in low attendance at a number of recent shows, does not mean that it has resulted in low attendance in all recent shows. So, there is a possibility that there are shows with high ticket prices that had high patronage.

D. Future ticket prices for well-known artists will continue to increase. Not necessarily. The ticket price is only increased to offset the guaranteed payments to well-known artists. This does not mean that future ticket prices for well-known artists will automatically increase. If the guaranteed payments remain the same, there would be no justification for an increase in ticket price.

E. The contracts between concert promoters and artists are not always based solely on revenue generated by ticket sales. This is the only one left and the language is not extreme. This is true. The contracts are also based on guaranteed payments per the information provided above. The information specifically states that independent promoters have had to increase their guaranteed payments to well-known artists, hence, guaranteed payments is included among other things that contracts between concert promoters and artists contain.