may be because of word strong - "strong referee" mean that whenever he says is true, because like in court the last word is always after the judge. But i would anyway choose A. Is there any explanation?
unfortunately there isn't any explanation, but like u said.........that the judge's word is d final word , and a judge can give a sense of direction , maybe in that case C sounds gud(the word "athourity" in the passage attached below gives an inkling).
Courtesy: "The nonstarters were
considered the ones who wanted stability, a
(30) strong referee to give them some position in the
race, a regulative hand to calm manic specula-
tion; an authority that can call things to a halt,"