In which phase of intensive rain is the asphalt roadway more slippery?

Why?

At the start of rainfall, water mixes with dust and oily deposits on the asphalt, creating a particularly slippery film. Heavy rain gradually washes these deposits away, so B and C do not describe this initial period of greatest slipperiness. The picture shows a wet, reflective road, but does not reveal how long it has been raining. Standing water remains a hazard later in the rainfall too.