Purchases categorized as leverage items in portfolio analysis have the following characteristic$($s$)\_\_\_\_\_\_\_\_.$

a$.$

switching suppliers is difficult

b$.$

supplier technology is important

c$.$

standard specification or commodity$-$type items, switching suppliers is difficult, and supplier technology is important

d$.$

standard specification or commodity$-$type items

e$.$

standard specification or commodity$-$type items and supplier technology is important