Static discharges occur when

a. a charge transfers without contact between materials

b. the air suddenly becomes charged between two oppositely charged objects

c. electrons are passed from one object through another by friction

B. the air suddenly becomes charged between two oppositely charged objects

Explanation:

When two equal and opposite charge density objects are placed near each other then due to huge charge density it will create large electric field in the air gap between two charge objects.

Due to this large electric field the electric dipoles of gases present in the air gap will experience large force in opposite direction due to which the dipole has tendency to breakdown.

Due to this breakdown of dipoles a discharge on two objects will occurs which is known as static discharge of air or breakdown of air.

So here correct answer will be

B. the air suddenly becomes charged between two oppositely charged objects

it would be c. predictability