In comparison with humans, the erythrocytes in frogs are

The correct option is "nucleated along with the presence of haemoglobin".

To understand why this is correct, we can compare the structure and characteristics of red blood cells (erythrocytes) between humans and frogs:
1. Presence of a Nucleus: Mature human erythrocytes (red blood cells) are enucleated, meaning they lack a nucleus. This adaptation provides more space within the cell to carry oxygen. In contrast, frog erythrocytes are nucleated, meaning they retain their nucleus even when fully mature.
2. Presence of Haemoglobin: Both human and frog erythrocytes contain the iron-rich respiratory pigment called haemoglobin, which binds to oxygen and gives the blood its characteristic red color. Without haemoglobin, the blood cells would not be able to transport oxygen efficiently throughout the body.

Therefore, compared to humans, the erythrocytes of frogs are characterized by being nucleated while still containing haemoglobin.