Determine the Intervals of the Domain Over Which the Function $( - \infty , \infty )$

Determine the intervals of the domain over which the function is continuous.
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A) $( - \infty , \infty )$
B) $( - \infty , 0 ) \cup ( 0 , \infty )$
C) $( - \infty , 1 ) \cup ( 1 , \infty )$
D) $( - \infty , 1 ] \cup [ 1 , \infty )$