Which of these is a subspace of the vector space of all functions f:R→Rf: \mathbb{R} \to \mathbb{R}f:R→R?
{f∣f(0)=1}\{f \mid f(0) = 1\}{f∣f(0)=1}
{f∣f(1)=0}\{f \mid f(1) = 0\}{f∣f(1)=0}
{f∣f(x)≥0 for all x}\{f \mid f(x) \geq 0 \text{ for all } x\}{f∣f(x)≥0 for all x}
{f∣f(0)=0 and f(1)=1}\{f \mid f(0) = 0 \text{ and } f(1) = 1\}{f∣f(0)=0 and f(1)=1}