Answer:
b. cómo se llama
c. cuál es tu nombre
they both can work in this situation.
Step-by-step explanation:
option b is talking in sign of respect since you don't know the person. It is talking in form of 'usted'
option c is talking like as if they alreayd know the person. it is talking in form of 'tu'
in reality both can be used
hope this helps :)