For this question, it is a little tricky because of the presented options as answers. Single-gene and chromosomal are both types of hereditary disorders and also are one of the most common ones. Complex can be referred to as multifactorial and duplex might be referring to two single-genes, which might be something rare since it isn't an actual type of hereditary disorder. The answer to this question would most likely be A. single-gene and chromosomal. Choosing all of the above would also mean choosing what isn't true, so A. would be the most likely correct one.