In the following question, select the missing number from the given alternatives :

127, 63, 31, 15, 7, ?

Answer : Option C

Explanation :

$frac{127-1}{2}=frac{126}{2}=63$ $frac{63-1}{2}=frac{62}{2}=31$ $frac{31-1}{2}=frac{30}{2}=15$ $frac{15-1}{2}=frac{14}{2}=7$