James has been contracted to set up a wireless network for a supermarket. The IT department of the supermarket wants James to develop a mesh network of APs $($Access Points$)$ to offer customers Internet access and selective discount coupons. James has decided that he will have to add additional security options for this purpose. Which one of the following will help James fix the issue?

a$.$

Use Geofencing security technique

b$.$

Establish a guest network with a separate SSID $($Service Set Identifier$)$

c$.$

Use wireless client isolation

d$.$

Use captive portal