The correct options are
A Rubidium
B Caesium
D Francium
A pyrophoric substance ignites spontaneously in air at or below 55 °C (130 °F). Examples are iron sulfide and many reactive metals including plutonium and uranium, when powdered or thinly sliced. Group I (Alkali) metals: Lithium, potassium, sodium, sodium-potassium alloy (NaK), rubidium, cesium, francium are pyrophoric in nature and need to be kept in kerosene for easy handling.