Solution
= Solution
{c}
\b[No, $[0,1]$ is not <open>.] Every basic <neighbourhood> $[a,b)$ of $1$ has $b>1$, so it contains points larger than $1$. Therefore $1$ has no <open> <neighbourhood> contained in $[0,1]$.
= Solution
{c}
\b[No, $[0,1]$ is not <open>.] Every basic <neighbourhood> $[a,b)$ of $1$ has $b>1$, so it contains points larger than $1$. Therefore $1$ has no <open> <neighbourhood> contained in $[0,1]$.