If the average (arithmetic mean) of a and b is 35 and the average of b and c is 80, what is the value of c − a? Choose the correct choice: A) 25 B) 50 C) 90 D) 140 E) it can not be determined from the information given .

Rationale: "- ( a + b = 70 ) b + c = 160 c - a = 90 c . 90"
Answer: C