Which of the following gives the correct number of multiplexers required to build a 32 x 1 multiplexer?

To build a 32x1 multiplexer, you would need five 2x1 multiplexers and four 4x1 multiplexers. Here's how:

1. First, you would use four 2x1 multiplexers to create two 4x1 multiplexers. This is because a 4x1 multiplexer can be made by using two 2x1 multiplexers and one additional 2x1 multiplexer as a selector.

2. Then, you would use two of the 4x1 multiplexers you just created and one additional 2x1 multiplexer to create an 8x1 multiplexer.

3. You would repeat this process to create a 16x1 multiplexer.

4. Finally, you would use two 16x1 multiplexers and one additional 2x1 multiplexer to create a 32x1 multiplexer.

So in total, you would need five 2x1 multiplexers (four for the initial 4x1 multiplexers and one for each subsequent stage) and four 4x1 multiplexers (two for the 8x1 multiplexer, one for the 16x1 multiplexer, and one for the 32x1 multiplexer).