What is the unit digit in (4137)754?  Choose the correct choice from the following answers:
A) 6 B) 5 C) 9 D) 13 E) 15

Rationale: "explanation : unit digit in ( 4137 ) 754 = unit digit in { [ ( 4137 ) 4 ] 188 x ( 4137 ) 2 } = unit digit in { 292915317923361 x 17114769 } = ( 1 x 9 ) = 9 c"
Answer: C