Answer: d.typically forms on warm, humid days
Explanation:
An ordinary cell thunderstorm is a storm that's typically not severe, scattered or isolated. The ordinary cell thunderstorm usually firms in the afternoon and typically forms on warm, humid days.
Ordinary cell thunderstorm usually takes place in less than an hour. Its initial stage is the cumulus stage and it's usually intense at its nature stage.
Therefore, the correct option is D.
