Laszlo has been hired to test a company's security methods. He starts an analysis of what is visible from outside of the network, then decides to see if he can find a way to gather information from within the network. He would like to access the router that is connected to the Internet but knows that he can't just walk right in$.$ Which of the following might allow him to access the router?

a$.$ Social engineering

b$.$ Phishing

c$.$ Whaling

d$.$ Harvesting