Which is the most likely explanation for a child exhibiting a heritable trait that neither parent exhibits?

Options:
The parents have recessive alleles, and the child inherited a dominant allele.
A mutation occurred, and the child exhibits a new trait due to the mutation
The trait is recessive, and the child inherited a recessive allele from each parent
A grandparent exhibits the trait, and the child inherited it directly from that person

A mutation occurred, and the child exhibits a new trait due to the mutation.