Given three coins are tossed.

Therefore,the sample space (ie) $2^3=8$ possible outcome

$S=\{HHH,HHT,HTH,HTT,THH,THT,TTH,TTT\}$

Given :

A=Three heads shows ={HHH}

B=Two heads and one tail show ={HHT,HTH,THH}

C=Three tail show ={TTT}

D=A head shows on the first toss={HHH,HHT,HTH,HTT}

Events A,C have only one sample point .Therefore,A and C are simple events.