Talking rotDespite its name, dry rot is anything but dry; it needs water to grow. It is caused by the fungus Serpula lacrymans, which colonizes damp wood in the form of red-brown fruit bodies. Wood consists of cellulose and lignin, and the fungus metabolizes the cellulose to its sugar components and eventually to carbon dioxide and water, which the fungus soaks up. The affected timber takes on a dull brown appearance, dries up and rapidly loses mechanical strength. Dry rot can threaten the structure of a building because it can spread beyond its source to penetrate the walls and brickwork.In the short term, timber affected with dry rot can be removed and the adjacent wood treated with a chemical fungicide. However, prevention is better than cure, and dry rot will not grow in an environment with less than 20 per cent moisture. Wet rot is more common in buildings than dry rot but is a far less serious problem because it cannot spread into the brickwork. Like dry rot, wet rot cannot grow in dry wood. Both dry and wet rot can usually be traced to a distinct source of rainwater ingress into a building, for example broken tiles, guttering or brickwork. Painting timbers with primer and top coat can stop water from penetrating wood, thereby preventing the germination of wood rot spores. However, an intact paint surface can mask fungal penetration that may have entered the wood at an exposed surface, for example where the timber is embedded in wet brickwork. The presence of dry rot can be confirmed by probing with a screwdriver, when the timber will easily give way, and also by tapping with a hammer, when it will sound hollow.

Question: The normal water content of wood is less than 20 per cent.
Options:
A. true, B. false, C. uncertain
Answer: "A"