Final answer:
A 'hot tower' can reach altitudes close to the start of the stratosphere. The tropopause marks the boundary of the troposphere and stratosphere, extending up to 12-15 km in the tropics. Intense hot towers can sometimes extend into the stratosphere, up to around 20 km (65,000 feet).
Step-by-step explanation:
According to the video, the term 'hot tower' is likely referring to a tall convective feature such as a thunderstorm or cumulonimbus cloud that can extend high into the atmosphere. These hot towers can reach altitudes close to the start of the stratosphere, which begins at the tropopause. The tropopause is located at different heights depending on the latitude, but typically it extends up to about 12-15 km (39,000 to 49,000 feet) in the tropics and is less at the poles.
However, some particularly intense thunderstorms, often in tropical regions, can punch through the tropopause and reach into the lower stratosphere. These are extraordinary cases and can reach altitudes up to around 20 km (65,000 feet), although this is not the norm. Given the options provided and understanding that the stratosphere starts above the tropopause, and that 30 km does not even get us out of the stratosphere while 20 km is an extraordinary height for a thunderstorm, the closest correct answer would be that a hot tower can go close to the start of the stratosphere.