Why is marijuana dangerous for teens?

Larry is taking a walk in the park, the pollen in the air makes him sneeze consistently what line of defense is his immune system exhibiting

*edit* i took the test and i picked a and it was incorrect for its c! rank the following suggestions for preventing std, in order of increasing effectiveness. 1) using latex condoms properly 2) using spermicidal foam or jelly with a monogamous partner 3) abstaining from sexual intercourse and genital contact a. 1, 2, 3c. 2, 1, 3

Which is the lipid molecule that controls what types of molecules can pass though?