Referring to the Ablon et al$.$ report on markets for cybercrime tools and stolen data, what definition $d$ the authors provide for the term "hacker market"?

An array of criminal exchanges that take place in a society

An online discussion site where people can hold open conversations about how to find and access secured data on the internet

The location in which a gray market operates

The collection of $($skilled and unskilled$)$ suppliers, vendors, potential buyers, and intermediaries for goods and services surrounding digitally based crimes