im not sure if im right (need someone to correct me if im wrong)

There is only one true statement : a, b, c or d
a) providers of HOPS are an important power in the beer production sector because there are many alternative substances that can be used instead. (false cause if there were alternatives, hops providers would not be so important)
b) suppliers of hops are an important power in the beer production sector because the evolution of the beer production sector depends on hops. (maybe true??)
c) providers of hops are not an important power in the sector. (false)
d) suppliers of hops are an important power for the sector because they are highly concentrated. (true?? this means that there are few and big providers)

REMEMBER: ONLY ONE TRUE STATEMENT . THANK YOU VERY, VERY, VERY MUCH FOR YOUR HELP!!! BEST REGARDS, SARAH (petitgirl17@hotmail.com) If you dont mind, i need to know how you got the answers: references, statistics... because i need to be sure they are accurate. Thank you so much!!!!