The switch statement is not initializing the value even if the case is True?

I want this switch statement to initialize the right value to the variable option but it is not initializing therefore not allowing the if statement to work.

#define arti 2.05

int main(void)
{
    char ch;
    float option = 0;

    while(ch = getchar())
    {
        ch = toupper(ch);

        switch(ch)
        {
            case 'A':
                option = arti; //value of arti is 2.05
                break;

            case 'B':
                option = beets;
                break;

            default:
                printf("Enter a valid value.\n");
                continue;
                break;
        }

       if(option == arti)
        {
            printf("arti printed successfully!\n");
        }

    }

    return 0;
}

The output i am getting is this:

a //input
Enter a valid value. //output

I don't know where is the problem i have made this code as short as possible to explain you the problem. Please help me with this.