Last month, Luiza's bank statement said that she had money in her account. Her bank balance was 109.32 rubles. This month, Luiza's bank balance is -87. 12 rubles. What does this mean?

OPTIONS-MAKE SURE TO CHECK THIS QUESTION ON KHAN ACADEMY
a-Luiza overdrew her account by 87.12 rubles
b-Luiza has 87.12 rubles in her account


plz answer this asap ;D