Judge the following is true or false If f is continuous on ( 0,1 ) then there is a c in (0,1) such that f(c) is a maximum value of f on (0,1)?

my friend tell me answer is true
but I think it is wrong
because according to the "Extreme Value Theorem"
the interval {a,b} should be "closed"
maximum is possible to be found
Is my thought wrong ?