In a geometric progression, the first term is 6 and the common ratio is 3. If Tk denotes its k-th term, what is the value of T1+T3+T5+⋯+T2n−1, the sum of the odd-numbered terms among the first 2n terms?
a) 43(32n−1)
b) 43(9n−1)
c) 3(3n−1)
d) 43(92n−1)