Which of the following subsets are subspaces of C[0,1]? Justify

i) { f $\displaystyle \in$ C[0,1] | f(0) = f(1)}

ii){ f $\displaystyle \in$ C[0,1]| f(0) = 0 and f(1) = 0}

iii){ f $\displaystyle \in$ C[0,1]|f(0) = 0 or f(1)=0}

iv){ f $\displaystyle \in$ C[0,1]| f is nondecreasing }