Answer:
I believe the best option is:
D. scorching
Step-by-step explanation:
The other options are not bad, they are just a bit generic. In writing, it is best to be as specific as possible. When something is hot enough to burn our skin, a good word that can help convey that meaning is "scorching". It can be used as an adjective or as an adverb. In the sentence "She sipped the scorching hot coffee," "scorching" functions as an adverb modifying the adjective "hot".
Note: even though "scorching hot" may sound redundant, it is a valid and correct expression.