$Z_{\text{eff }}$ for valence electron of $\mathrm{Ga}=a$

$Z_{\text{eff }}$ for valence electron of $\mathrm{Al}=b$

$Z_{\text{eff }}$ for valence electron of $\mathrm{Ca}=\mathrm{c}$

choose the correct option (s)

10 of the electrons in calcium are n-2 or lower in energy and are regarded as inner core electrons. Ca has a Zeff of 2.85.
Additionally, Ca's Zeff is 8.2136. Ga has a higher Z effective or nuclear charge than any of them. So the first two choices are the right ones.