Based on this information, what is Josiah's phenotype for the sickle-cell disease trait?
Aa not having sickle-cell disease
This passage describes the sickle-cell disease trait in humans:

In a group of humans, some individuals have sickle-cell disease and others do not. In this group, the gene for the sickle-cell disease trait has two alleles. The allele A is for not having sickle-cell disease, and the allele a is for having sickle-cell disease.
Josiah, a human from this group, does not have sickle-cell disease. Josiah has one allele for not having sickle-cell disease and one allele for having sickle-cell disease.
All organisms have pieces of hereditary material called genes, which are passed from parents to offspring. Genes contain instructions for building the parts of an organism. An organism's genes affect its observable traits, including its appearance, its behavior, and which diseases it may have. Genes may have different alleles, or forms, that can cause different versions of a trait.
For example, flower color is a trait in pea plants. The gene for this trait has two possible alleles. Each allele is represented by an uppercase or lowercase letter. The allele F is for purple flowers, and the allele f is for white flowers. Each pea plant has two alleles for the flower color gene—one allele inherited from each parent.
An organism's genotype for a gene is its combination of alleles for that gene. So, a pea plant may have a genotype of FF, Ff, or ff for the flower color gene.
An organism's phenotype for a trait is its observable version of that trait, which depends on the organism's combination of alleles. A pea plant may have a phenotype of purple flowers or white flowers for the flower color trait.
An organism's phenotype for a trait is its observable version of that trait. Josiah's observable version of the sickle-cell disease trait is not having sickle-cell disease. So, Josiah's phenotype for the sickle-cell disease trait is not having sickle-cell disease.