Which conditions indicate a contaminated runway for takeoffs?

For takeoffs, a runway is considered contaminated when it is compromised by substances that reduce friction, such as snow, slush, or standing water. These conditions can significantly affect the aircraft's performance during the takeoff roll by increasing the stopping distance and potentially leading to degraded control during the initial phases of flight. Snow and slush can create a slippery surface, while standing water can lead to hydroplaning, which impairs the aircraft's ability to accelerate effectively and safely become airborne.

The other options do not indicate contamination: a clear runway would imply optimal conditions with full traction, dry and paved surfaces suggest ideal takeoff conditions, and rain showers may not accumulate to a level that compromises runway performance unless they create pooling water or significant wetness. Thus, the presence of snow, slush, or standing water directly correlates with the hazards associated with a contaminated runway.