I think it is stage 2
At stage two, the skin breaks open, wears away, or forms an ulcer, which is usually tender and painful. The sore expands into deeper layers of the skin. It may appear as a scrape, blister, or a shallow crater in the skin. At times this stage looks like a blister filled with clear liquid. Also at this stage some skin may be damaged beyond repair or may die.
A, the others are unrealistic speeds.
Honestly it would be the Exosphere<span> but since that's not one of the choices it would be the Thermosphere. </span>
