Which of the following is not a metric space on C = {f: [0, 1] → R is a continuous function}
1
d(f, g) = sup(|f(x) - g(x)| : x ∈ [0, 1])
2
d(f, g) = inf(|f(x) - g(x)| : x ∈ [0, 1])
3
d(f, g) = \(\int_0^1\)|f(x) - g(x)|
4
d(f, g) = max(|f(x) - g(x)| + |f'(x) - g'(x)| : x ∈ [0, 1])