A. O$_3$ in stratosphere is not completely effective in shielding us from UV-B B. UV-A is biologically least harmful. C. Chapman mechanism deals with only O$_3$ formation in stratosphere. D. Sunscreen lotions either reflect or absorb or scatter UV-B and UV-A E. UV-B helps in dissociation of O$_3$ molecule in stratosphere.
Choose the correct answer from the options given below.