Select the correct fact out of the following

The force of the nucleus experienced by the electrons of valence shell is decreased by electrons of the inner core. It is called Screening or Shielding effect.

The valence electrons 2s1 of Li experience a force of nucleus less than applied by +3 charge of protons due to 1s2 pair.

From Li to F the shielding effect of core electrons remains the same. Increase in one electron in same valence shell and one proton in nucleus increase the attraction of valence shell and nucleus o decrease the size.

All the facts are correct.