Which of the following injuries to the periodontium is considered to be chemical?

When titrating the FiO2 level downward from 100% to 40%, what is the maximum increment that should be applied between estimates of oxygenation?

a. 5% b. 10% c. 20% d. 25%

If susceptibility is ____ and severity is ____, perceived threat is ____.?

A) low; low; moderate B) low; high; low C) high; high; high D) moderate; low; high