Final answer:
The statement that two layers of underlayment should be applied for roof slopes from 2:12 up to 4:12 (excluding 4:12) is true, as it provides better protection against water penetration for low-sloped roofs. The correct option is a.
Step-by-step explanation:
The question relates to the application of underlayment on a roof with a slope between 2:12 and 4:12 (but not including 4:12). The statement is True.
For roof slopes that are in the range from 2:12 up to but not including 4:12, the installation of two layers of underlayment is recommended to provide adequate protection against water penetration.
This is a common construction practice to ensure that such low-sloped roofs have additional layers of water-shedding material beneath the outer roofing material, such as shingles or tiles. The correct option is a.