Use the difference of angles identity cos open parentheses A minus B close parentheses equals cos A cos B plus sin A sin B to expand and simplify the expression cos open parentheses fraction numerator 3 straight pi over denominator 4 end fraction minus straight pi over 3 close parentheses. A.) fraction numerator short dash square root of 2 plus 1 over denominator 4 end fraction B.) fraction numerator short dash square root of 2 plus square root of 6 over denominator 4 end fraction C.) fraction numerator square root of 2 minus square root of 6 over denominator 4 end fraction D.) fraction numerator short dash square root of 2 minus 1 over denominator 2 end fraction