If all use of ozone-depleting chemicals is stopped, it should take about for Earth’s stratospheric ozone layer to recover.

A. 60 years

B. 6 years

C. 1,000 years

D. 1 year

the cell theory states that all living things including animals, as well as plants, are made of cells.

the answer to your question is tooth decay.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.