In which of the following, carbon uses \(sp^3\) hybrid orbital for bond formation with oxygen?
Show Hint
A carbon atom bonded to oxygen through
\[
\boxed{\text{only single bonds}}
\]
is generally
\[
\boxed{sp^3\text{-hybridized}.}
\]
A carbonyl carbon
\[
(\mathrm{C=O})
\]
is always
\[
\boxed{sp^2\text{-hybridized}.}
\]