When an F atom becomes an F-ion, the Fatom gains a proton
gains an electron
loses an electron
loses a proton

When an F atom becomes an F-ion, the F atom gains an electron.

Learn more at: link

The Fluoride ion given has a -ve charge onto it. Thus in order to become stable Fluorine gains an electron. Thus option b is correct.

The elements in the periodic table try to attain the stable noble gas configuration in the order to become stable. The noble gas configuration has the elements to be less reactive.

When the atom loses an electron in order to become more stable,  a +ve charge has been implemented onto the ion.

When the atom gains an electron to become stable, a -ve charge has been added to the ion.

The Fluoride ion given has a -ve charge onto it. Thus in order to become stable Fluorine gains an electron. Thus option b is correct.

For more information about atom, refer to the link:

link