Answer:
D. They have very similar properties.
Explanation:
A. They have the same atomic mass.
⇒ This is false, every element has a different atomic mass.
B. They have very different properties
⇒ This is false. elements in the same group have similar properties
C. They have the same atomic number.
⇒ Every element has a unique and different atomic number
D. They have very similar properties.
⇒ This is correct. Elements in the same group usually have similar properties, because they have the same number of electrons in the outermost electron shell.
