Five persons are sitting in a row facing north. Driver and Electrician sit at both ends of the row. The plumber sits next to the right of the carpenter. The mechanic sits next to the immediate left of the electrician. The carpenter sits exactly between the driver and the plumber. Who among the following person sits in the middle of the row?

 Driver and electrician are sitting at both ends of the row, so there will be two cases:  Carpenter is sitting exactly between the driver and the plumber and the plumber is sitting next to the right of the carpenter.  Since Mechanic is sitting to the immediate left of Electrician, Case-2 is not possible. Final arrangement of Case-1 is shown below. From the above arrangement, it is clear that Plumber is sitting in the middle. Hence, the correct answer is (B).