What will be the biggest problem if there is no electricity?

What will be the biggest problem if there is no electricity?

There would be no power to use your fridge or freezer, telephone lines would be down and phone signal lost. Your mobile phones will be useless as the battery dwindles, with no back up charging option. Your gas central heating won't work and your water supply would soon stop pumping clean water.

The one that most represents the earths mantle would be the skin since the mantle is the upper part of the earths depths which is just like the skin of an apple.