Which is a main function of lipids? providing energy storage transmitting genetic information forming bone and muscles fighting infection and disease

Answer is providing energy storage.

Lipids are naturally occurring group of molecules which include fats, oils and some steroids. They composed of fatty acids bonded to a wide range of other compounds. Lipids are important constituent of the diet. It stores energy. Storage lipids are triglycerides made up of three fatty acids and a glycerol. Fatty acids are in non-esterified form and are released from triglycerides to provide energy  from stored lipids and to form the structural components for cells.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.