Question

where in the laboratory is long, unrestrained hair most likely to be a safety concern?
near an open flame
close to a fume hood
next to a concentrated sodium chloride solution
by a cabinet that contains flammable liquids

Explanation:

Long, unrestrained hair near an open flame poses a fire hazard as hair can easily catch fire. A fume hood is for ventilation of harmful gases, sodium chloride solution is non - hazardous in this context, and a cabinet with flammable liquids (if closed) doesn't directly threaten hair like an open flame.

Answer:

near an open flame