GKFix MCQ Question

Which of the following is a key difference between isotopes and isobars?

• A. Isotopes are of different elements, isobars are of same element
• B. Isotopes have same atomic number, isobars have same mass number
• C. Isotopes are of same element, isobars are of different elements
• D. Isotopes have same mass, isobars have same atomic number