Final answer:
To protect cooling tower wood from biological attack, the use of biocides is recommended, as they prevent harmful organism growth. Other substances like creosote may be regulated due to environmental concerns, and redwood is a naturally resistant material. Nails are unrelated to the wood's preservation.
Step-by-step explanation:
To reduce attack on cooling tower wood, a limited amount of specific chemicals or treatments should be used. One effective treatment is the use of biocides, which are chemical substances designed to kill or inhibit the growth of harmful organisms, such as bacteria and algae, that contribute to the degradation of the wood and the efficiency of the cooling towers. In contrast, treatments such as creosote, which is a wood preservative, may be considered, but it can have environmental impacts, and its use may be limited or regulated. Redwood, being a more resistant material, may also reduce the need for additional treatments. The use of nails or other fastening materials is not related to the preservation or treatment of the wood against biological attack.