Adrawback to superconductors.

a. they perform well only at very low temperatures.

b. they are made from extremely expensive materials.

c. they have very few uses.

d. they are dangerous to use.

Option (A) is the correct answer.

Explanation:

A conductor that conducts heat and electricity very effectively at very low temperature is known as a super conductor.

There occurs no resistance in a super conductor.

For example, magnesium diboride, mercury, lead etc are super conductors.

Since, super conductors only work at temperature which are lower than their critical temperature this makes them less useful.

Therefore, we can conclude that a drawback to superconductors is that they perform well only at very low temperatures.

Explanation:

The circulatory system moves blood throughout the body and has no normal microbiota. The lymphatic system moves fluids from the interstitial spaces of tissues toward the circulatory system and filters the lymph.

This fluid is called lymph. There is no heart-like pump for the lymphatic system. Instead, as you breathe and move your muscles, the lymph continuously gets pushed toward the heart from the outer reaches of your body. (It's very much like how blood depleted of oxygen moves back toward your heart through the veins.)

Lymph (from Latin, lympha meaning "water"[1]) is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to the central circulation. Interstitial fluid – the fluid which is between the cells in all body tissues[2] – enters the lymph capillaries. This lymphatic fluid is then transported via progressively larger lymphatic vessels through lymph nodes, where substances are removed by tissue lymphocytes and circulating lymphocytes are added to the fluid, before emptying ultimately into the right or the left subclavian vein, where it mixes with central venous blood.

Since the lymph is derived from the interstitial fluid, its composition continually changes as the blood and the surrounding cells continually exchange substances with the interstitial fluid. It is generally similar to blood plasma, which is the fluid component of blood. Lymph returns proteins and excess interstitial fluid to the bloodstream. Lymph also transports fats from the digestive system (beginning in the lacteals) to the blood via chylomicrons.

Bacteria may enter the lymph channels and be transported to lymph nodes, where they are destroyed.[clarification needed] Metastatic cancer cells can also be transported via lymph.