Amir wants to change this model to represent a different isotope of oxygen. How could he make this change? A
add one green candy
B
add one red candy
rearrange the blue candies
D
take away two blue candies

A  add one green candy

Explanation:

Sometimes elements have variants that have different mass numbers from one another. These are called isotopes and they happen because the neutrons in the nucleus of the element are different in number.

If Amir wanted to represent a different isotope of oxygen he should change the number of neutrons in the nucleus.

Seeing as the neutrons are green in color, he can add one green candy to the model to create an isotope of Oxygen with a greater mass number.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.