Explanation:

Correct Option is 3:2346

The series followed here is :
147 x 2-1 = 293
⇒293 x 2 + 1 = 587
⇒ 587 x 2-1 = 1173
⇒ 1173 x 2 + 1 = 2347
⇒2347 x 2-1 = 4693
Here, It should be '2347' instead of '2346'.
Hence, "2346" is the correct answer.