A template of a Venn diagram representing common and differentiating characteristics of covalent and ionic bonds is shown.

Two overlapping circles are shown. On top of the left-hand circle Ionic Bond is written and on top of the right-hand circle Covalent bond is written. The non-overlapping space on the left is marked A, the overlapping space is marked B and the non-overlapping space on the right is marked C.

Which of the following characteristics can be written only in space A?

a
Formed between atoms of similar electronegativities

b
Formed between two metal atoms mostly found on the left of the periodic table

c
Formed between two non-metal atoms mostly found on the right of the periodic table

d
Formed between an atom that tends to lose electrons and an atom that tends to gain electrons