Final answer:
A woman with type M blood can have a child with type N blood if she is a hidden carrier of the LN allele and the father provides an LN allele, due to the codominance of the LM and LN alleles in the MN blood group system.
Step-by-step explanation:
A woman with type M blood can have a child with type N blood in the context of MN blood groups when both the mother and father carry the codominant alleles LM and LN respectively. Codominance means that both alleles in a heterozygous individual are fully expressed, so a woman who has type M blood (genotype LMLM) could carry a hidden LN allele passed down from her parents. If the father of her child has either type N blood (genotype LNLN) or is a heterozygous type MN (genotype LMLN), the child could inherit the LN allele from the father and have type N blood (genotype LNLM or LNLN) if the mother contributes an LN allele as well.