A child has a blood type of O. Can the mother of that child have a blood type of AB? Explain your answer.

Explanation:

Yes they can. An AB parent can indeed sometimes have an O child. But it is by no means common. In fact it would be fair to say that it is exceedingly rare.

The one exception is in certain Asian groups. Some of these folks have a rare version of the ABO blood type gene called cis-AB. People with this gene version have an AB blood type but can easily have an O child.

a covalent bond, specfically triple bond