I’ve answered this
question before so if these are the choices to the question presented:
An oxygen atom double-bonded to a carbon atom, with a hydrogen atom
single-bonded to the same carbon atom.
A hydrogen atom covalently bonded to an oxygen atom, which is
covalently bonded to a carbon in the carbon chain.
A carbon atom single-bonded between two other carbon atoms,
with an oxygen atom double-bonded to the central carbon atom as well.
An oxygen atom single-bonded between two carbon atoms within
a carbon chain.
Then, the answer would be “a hydrogen atom covalently bonded to an oxygen atom,
which is covalently bonded to a carbon in the carbon chain.”
