To model Giselle's situation with a linear function, we can set up the function with b representing the balance in her account and x representing the number of times she uses the club.
She starts with $190 and each time she uses the club, $10 is deducted from her account. Therefore, the correct equation can be expressed as:
\[ b = 190 - 10x \]
This means her balance b decreases by $10 for each use x of the athletic club.
So among the options you've provided, the correct function is:
b = 190 - 10x.