How would you explain the lower atomic radius of Ga as compared to Al?

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1. AGallium has more protons in its nucleus compared to aluminum, leading to a higher effective nuclear charge and
2. BGallium has fewer electrons in its outermost shell compared to aluminum, resulting in a smaller atomic radius.
3. CGallium experiences greater electron-electron repulsion in its outer shell compared to aluminum, leading to a
4. DThe presence of d-orbitals in gallium leads to greater electron delocalization, resulting in a smaller atomic