Phospholipids are important components of . 1) the plasma membrane of cells
2)the ring structure of steroids
3) the waxy covering on leaves
4)the double bond in hydrocarbon chains

1) the plasma membrane of cells

Explanation:

Phospholipids are made of a phosphate group and fatty acid chain. The phosphate group is hydrophilic (attracted to water), while the fatty acid group is hydrophobic (repelled by water). This is important to the membrane because it allows for the cell to interact with the water inside and outside the cell. Therefore, the answer is number 1.

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.