Your supervisor has asked you to call the cabling contractor your company uses and make an appointment to install some new twisted$-$pair cable runs. In addition to asking how many cable runs you need pulled, the contractor asks you if you need plenum or PVC$.$ Under which of the following conditions might the local building code require that a data network use plenum cable?

Question $77$ options:

When cable runs exceed the maximum length specified by the physical layer specification

When cables must run through air ducts

When cables run near to devices that generate electromagnetic interference $($EMI$)$

When multiple cables run through the same conduit