A. distance of the outermost electron(s) from the nucleus
B. size of the positive nuclear charge
C. ability to attract shared electron(s)
D. screening effect of the inner electron(s)
Correct Answer: Option C
C. ability to attract shared electron(s)
Explanation
These 3 factors affect ionization energy:
Size of the positive nuclear charge
Size of atom (the distance of the outermost electron from the nucleus)
Screening effect of inner shell electrons