If $$s$$ is a string over $${\left( {0 + 1} \right)^ * }$$ then let $${n_0}\left( s \right)$$ denote the number of $$0'$$ s in $$s$$ and $${n_1}\left( s \right)$$ the number of $$1'$$s in $$s.$$ Which one of the following languages is not regular?

Consider the machine $$M:$$ The language recognized by $$M$$ is:

The following finite state machine accepts all those binary strings in which the number of $$1's$$ and $$0's$$ are respectively

Consider the following deterministic finite state automation $$M.$$

Let $$S$$ denote the set of seven bit binary strings in which the first, the fourth, and the last bits are $$1$$. The number of strings in $$S$$ that are accepted by $$M$$ is