4.) make proteins.
Explanation:
Lipids perform functions both within the body and in food. Within the body, lipids function as an energy reserve, regulate hormones, transmit nerve impulses, cushion vital organs, transport fat-soluble nutrients, protection, insulation and cell division
The lipids of the SC are structured in the intercellular spaces of the mammalian epidermis in ordered layers, called lamellae, which have been postulated to prevent water loss.
Membrane lipids participate in the interaction of proteins with the cell barrier. They don't make the proteins.
I think there's a typing error in choice 1. It should be 'energy reserve' - which is a function of lipids.