Wangycbest

Premise: Televisions are made in both V and B, and B imports TV from V.  The number of televisions sold in B keeps constant.  These TV's come from both B and V. the number of TV assemblers in B decreases.

Conclusion: TV imports from V to B has increased.

The assumption is that if TV assemblers in B are fewer, there will be fewer TV made in B.  A further assumption is that the efficiency of TV assemblers in B has not changed (answer C).

Wangycbest

If you use negation method, you would find that after negating C, the argument falls apart. If assemblers in B become more efficient, they can produce the same amount or more TV than before, even with a lower number of total assemblers.