Which of the following materials should be avoided to ensure safety?

Strong acids should be avoided to ensure safety because they can cause severe chemical burns, are reactive with various materials, and can release harmful fumes when they come into contact with certain substances. In an industrial refrigeration setting, the presence of strong acids poses serious risks to personnel safety and equipment integrity.

While there are certainly safety concerns surrounding alkaline metals, which can be highly reactive and explosive in the presence of moisture or air, and while glass and ceramics can pose a risk of breakage and sharp edges, strong acids are particularly hazardous due to their corrosive nature and the immediate harm they can inflict upon contact. Hence, the correct response emphasizes the dangers associated with strong acids in a safety context.