Answer : Option A

Explanation :

---------------------------------------------------------------------------------------
Solution 1
---------------------------------------------------------------------------------------
Total number of outcomes possible when a coin is tossed = 2 (∵ Head or Tail)
Hence, total number of outcomes possible when two coins are tossed, n(S) = 2 × 2 = 4
(∵ Here, S = {HH, HT, TH, TT})
E = event of getting heads on both the coins = {HH}
Hence, n(E) = 1

$MF#%\text{P(E) = }\dfrac{\text{n(E)}}{\text{n(S)}} = \dfrac{1}{4}$MF#%

If n fair coins are tossed,

Total number of outcomes in the sample space = $MF#%2^n$MF#%

The probability of getting exactly r-number of heads when n coins are tossed = $MF#%\dfrac{n_{C_r}}{2^n}$MF#%