If the value of a is 0.9, then value of ß is ___________

The answer is not option D but rather option A which is 9.
This is because the relationship between alpha and beta is : Beta = [ alpha / (1 - alpha)].
>> 0.9/(1-0.9)
0.9/0.1 =9

Correct answer is A which is 9

Answer is 9
As.. Beta = alpha/(1-alpha)
=0.9(1-0.9)
=0.9/0.1
=9

If the value of alpha is 0.9, then a per the relation between alpha and beta, shouldn't the answer be "9"?
Because beta = alpha/(1-alpha) is the relation and after calculation we get:
beta = 0.9/(1-0.9) = 0.9/0.1 = 9, which is the answer.

But while solve through formula of beta it comes out to be 9 not 90 can you explain how it becomes 90

But while it comes to be 9 then how it will 90