A small island country with less than 20,000 cars has decided to reissue the license plates for its cars and has decided on the following rules for assigning numbers and letters to the license plates. Each plate will have 7 character positions that each must be filled. The leftmost character position will hold a letter from the set {D, E, H, G, X}. The next three positions will hold integers from the set {0, 1, ..., 9} but none of the integers can be repeated. The rightmost three positions must be entirely from the set {I, V, X} or entirely from the set {P, Q, R}, with repetition allowed in either case. For example, a valid plate would be G 027 XXI and an invalid plate would be G 337 PQX (two rules violated). What is the maximum number of different license plates following the rules?

a. 270,000
b. 2,624,400
c. 3,645,000
d. 194,400