If, due to structural conditions, horizontal vents are less than 6 inches above the flood rim level of a fixture, the horizontal portion shall be installed with ________?
1) a slope of 1/4 inch per foot towards the fixture
2) a slope of 1/8 inch per foot towards the fixture
3) a slope of 1/2 inch per foot towards the fixture
4) a slope of 1/16 inch per foot towards the fixture