Answer:b. Facilitated transport
Explanation:in the usual activities of the cell,it's cell membrane is responsible for the movement of substance in and out of the cell.
Such substances include nutrients,water, oxygen etc.
The plasma membrane select the substances that it allows into the cell thus it is said to be selectively permeable.
The plasma membrane of the cell has a phospholipid bilayer made up of cholesterol, proteins and glycoproteins.
The proteins on the membrane are useful for facilitated diffusion.
In this diffusion process,the proteins helps to carry large molecules across the cell membrane.such molecules includes glucose,amino acids etc.
In the process energy is not expended so it is a type of passive transport.
Is a large molecule, or macromolecule, composed of many repeated subunits.Because of their broad range of properties, both synthetic and natural polymers<span> play essential and ubiquitous roles in everyday life.</span>
Vitamin A; it is a soluble vitamin in fatty bodies, which can not be released in the urine as other vitamins normally do, it is said that we consume large quantities in an inactive form since this is necessary for many human body processes such as vision, formation and maintenance of skin cells, the immune system, growth and even lactation and embryonic development, therefore it is not necessary to be active to consume large amounts of this vitamin.
