Telepone wires sag in summer. Why​

The telephone wires will sag in summer due to expansions. While putting up the wires between the pole care is taken care in winter they are kept light so that they may not sag too much. ... So telephone wires will sag in summer due to expansion while you do suspect because of because of because of sighing expansion.

Inelastic is the answer your looking for.

Ithink it is a. but i'm not 100 percent sure.