Final answer:
Beta-thalassemia major is the type of beta thalassemia that is most likely to show nucleated RBCs in the peripheral blood.
Step-by-step explanation:
Nucleated RBCs are most likely to be seen in the peripheral blood of patients with beta-thalassemia major, also known as Cooley's anemia. Beta-thalassemia is an inherited condition where there is a decreased synthesis rate of the beta chain of globin, resulting in low levels of hemoglobin. The abnormal maturation of RBCs in beta-thalassemia leads to the release of immature cells with a nucleus into the bloodstream.