Final answer:
A hybrid is an organism with one set of chromosomes from two different species, unlike a polyploid which has additional sets of chromosomes from the same or different species.
Step-by-step explanation:
An organism that has one set of chromosomes from two different species is best described as a hybrid. A hybrid results from the crossbreeding between two different species and contain genetic material from both parents.
This is different from polyploidy, where an organism has more than two sets of chromosomes, which could be either from the same species (autopolyploidy) or from different species (allopolyploidy). Mutants are organisms with changes in their DNA sequence, and transgenic organisms have had genes from another species inserted into their genome. Polyploids, for example, are common in plants and can have multiple sets of chromosomes that result in larger, more robust physical characteristics.