The correct option is D
When three coins are tossed simultaneously, the possible outcomes are (H,H,H),(H,H,T),(H,T,H),(T,H,H),(H,T,T),(T,H,T),(T,T,H),(T,T,T), which are equally likely.
∴ Total number of outcomes = 8
Let E be an event of getting at least two tails.
The outcomes favourable to event E are (H,T,T),(T,H,T),(T,T,H),(T,T,T).
∴ Number of outcomes favourable to E = 4
P(E)=No of favourable outcomesTotal no of outcomes
Hence, the correct answer is option (d).