Sigma-Algebra Generated by Unitary Subsets and Its Measurable Functions

Let X be a non-empty set and let E denote the collection
of all unitary subsets of X, that is,
E = {{x} ; x $\in$ X}.

(a) What is the $\sigma $ -algebra generated by E?
(b) If A is the $\sigma $-algebra generated by E, what are the functions A-measurable f : X $\rightarrow $ R?

The answer is accepted.
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