The passage below is accompanied by a set of questions. Choose the best answer to each question.

 

Plasma is the often-forgotten part of blood. White blood cells, red blood cells, and platelets are important to body function. But plasma also plays a key role. This fluid carries the blood components throughout the body.

Plasma is the largest part of your blood. It makes up more than half (about 55%) of its overall content. When separated from the rest of the blood, plasma is a light-yellow liquid. Plasma carries water, salts and enzymes.

The main role of plasma is to take nutrients, hormones, and proteins to the parts of the body that need it. Cells also put their waste products into the plasma. The plasma then helps remove this waste from the body. Blood plasma also carries all parts of the blood through your circulatory system.

Plasma is a critical part of the treatment for many serious health problems. This is why there are blood drives asking people to donate blood plasma.

 Along with water, salt, and enzymes, plasma also contains important components. These include antibodies, clotting factors, and the proteins albumin and fibrinogen. When you donate blood, healthcare providers can separate these vital parts from your plasma. These parts can then be concentrated into various products. These products are then used as treatments that can help save the lives of people suffering from burns, shock, trauma, and other medical emergencies.

 The proteins and antibodies in plasma are also used in therapies for rare chronic conditions. These include autoimmune disorders and haemophilia. People with these conditions can live long and productive lives because of the treatments. In fact, some health organisations call plasma "the gift of life."
If you want to donate plasma to help others in need, you will go through a screening process. This is to make sure your blood is healthy and safe. If you qualify as a plasma donor, you'll spend about an hour and a half at a clinic on every follow-up visit.

During the actual blood donation process, your blood is drawn through a needle placed in a vein in one arm. A special machine separates the plasma and often the platelets from your blood sample. This process is called plasmapheresis. The remaining red blood cells and other blood components are then returned to your body, along with a little saline (salt) solution.

 People with the blood type AB are in the greatest demand for plasma donation. They make up just 2 in 50 people, their plasma is universal. This means their plasma can be used by anyone.

Plasma donation requires a commitment both in the amount of time for each donation and frequency of donation. Typically, it takes between one and three hours to donate source plasma, and plasma can be donated twice within a seven-day period. Whole blood donation takes less time—under 30 minutes—and donors donate less frequently—no more than once in eight weeks. The programs may fit into a donor's life differently at various times in the donor's life, and are equally important in helping to fulfill a vital medical need.

Which one of the following comes closest in meaning to the author’s understanding of plasma?