Because $$39$$ is an odd number, one of the two numbers must be an even prime number $$2$$. The other number is $$39-2=37$$, and their difference is $$35$$.  So the answer is $$\text{B}$$. 
If the sum of two prime numbers is $$39$$, the difference between these two prime numbers will be ． 
Options:
a. $$29$$ 
b. $$31$$ 
c. $$33$$ 
d. $$35$$ 
e. $$37$$ 