Consider the following combinational function block involving four Boolean variables x, y, a, b where x, a, b are inputs and y is the output.f (x, y, a, b)(                if (x is 1) y = a;                else y = b;}Which one of the following digital logic blocks is the most suitable for implementing this function?

The most suitable digital logic block for implementing this function is a Multiplexer (MUX).

Here's why:

1. A multiplexer is a combinational circuit that selects binary information from one of many input lines and directs it to a single output line. The selection of a particular input line is controlled by a set of selection lines.

2. In the given function, the output 'y' is either 'a' or 'b' depending on the value of 'x'. This is exactly what a multiplexer does.

3. If we consider 'x' as the selection line, 'a' and 'b' as the input lines, and 'y' as the output line, the function can be implemented.

4. When 'x' is 1, 'a' is selected and when 'x' is 0, 'b' is selected. This is the same operation performed by a 2-to-1 multiplexer.

So, a Multiplexer is the most suitable digital logic block for implementing this function.