This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Passage: Reptiles such as adders and vipers live up to the snow line; because they cannot bear the cold temperatures they hibernate underground and soak up the warmth on rocky ledges. The high-altitude Alpine salamanders have adapted to living above the snow line by giving birth to fully developed young rather than laying eggs. Brown trout can be found in the streams up to the snow line. Molluscs such as the wood snail live up the snow line. Popularly gathered as food, the snails are now protected. Question: Why do reptiles only live up to the snow line?
they cannot bear the cold temperatures

Passage: Further problems hampered the Arctic project after the commencement of drilling in 2012, as Shell dealt with a series of issues that involved air permits, Coast Guard certification of a marine vessel and severe damage to essential oil-spill equipment. Additionally, difficult weather conditions resulted in the delay of drilling during mid-2012 and the already dire situation was exacerbated by the "Kulluk" incident at the end of the year. Royal Dutch Shell had invested nearly US$5 billion by this stage of the project. Question: What conditions caused the delay of drilling in mid-2012?
difficult weather

Passage: The proportion of non-repetitive DNA is calculated by using the length of non-repetitive DNA divided by genome size. Protein-coding genes and RNA-coding genes are generally non-repetitive DNA. A bigger genome does not mean more genes, and the proportion of non-repetitive DNA decreases along with increasing genome size in higher eukaryotes. Question: What are two types of non-repetitive DNA?
Protein-coding genes and RNA-coding genes