Because group disability nsurance $($DI$)$ coverage is usually offered to the members of the group without medical underwriting. It is important to the issuing insurance company that the group members have some element of commonality, so that their risk can be pre$-$assessed based on criteria other than actuarial tables.For that reason, group insurance is not just offered to anyone who wishes to take advantage of it$,$ but to potential lives insured who exhibit some common trait such as:$1.$ Work for the same employer$2.$ Live in the same community$3.$ Work in the same industry$4.$ Are alumni of the same universitySeled one:a$.1\mathrm{.}2\mathrm{.}3$b$.1,2\mathrm{.}4$c$2,34$d$.1\mathrm{.}3,4$