A shoplifter and a security guard are playing a simultaneous game. If the shoplifter steals and the security guard is vigilant, the shoplifter gets caught, suffers a loss of $20,$ and the security guard gets a bonus worth $15.$ If the shoplifter steals and the security guard is not vigilant, the shoplifter does not get caught and gains $15$ and the guard loses $5.$ If the shoplifter does not steal and the guard is vigilant, the guard loses $3$ for the effort, while the shoplifter gains nothing and if the shoplifter does not steal and the guard is not vigilant, neither gain anything

Use Scenario $15-7$

If the security guard knows that the shoplifter has chosen to steal, the security guard's best response would be

a$.$ to be vigilant.

b$.$ to hide.

c$.$ to sleep.

d$.$ to not be vigilant.