2 and 4 should be correct
The elements carbon, nitrogen and oxygen are crucial to life on the earth, at least. These elements are MOST IMPORTANT ELEMENTS ON THE EARTH.
There are six most important elements such as carbon, nitrogen, oxygen, hydrogen, phosphorus and sulfur. These are also referred as SPONCH elements.
A) Combine to form carbohydrates
Answer: elastic fibers
Explanation:
Elastic fibres are the essential durable component present in mammalian connective tissueand functions to provide proper pulmonary, cardiovascular and intestinal system structure and function. Their structural function is to provide elastic recoil and resilience for the tissues.
Elastin fibers ahve two main including microfibrils and elastin containing fibrillin play a mechanical and structural role in the arteries, and their important function is to provide the tissues with resilience and elasticity.
Hence, elastic fibers helps arteries to adapt to changes in blood pressures that accompany the heartbeat.