If the resultant of the vectors \[3\widehat{i}+4\widehat{j}+5\widehat{k}\] and \[5\widehat{i}\text{ }+\text{ }3\widehat{j}\text{ }+\text{ }4\widehat{k}\] makes an angle \[\theta \] with x-axis, then \[cos\text{ }90{}^\circ \] is

• A. 0.07     
• B.        0.574
• C. 0.111   
• D.        0.123