If one of the angles of an isosceles triangle measures \[30{}^\circ ,\] then what are the possible differences between the measures of its unequal angles?

• A.  \[20{}^\circ \]and \[70{}^\circ \]               
• B.  \[45{}^\circ \] and \[90{}^\circ \]    
• C.  \[30{}^\circ \]and \[90{}^\circ \]               
• D.  \[45{}^\circ \]and \[105{}^\circ \]