Укажите число, обратное сумме чисел \(\displaystyle c\) и \(\displaystyle d{\small.}\)

• \(\displaystyle \frac{1}{c+d}\)
• \(\displaystyle \frac{c}{d}\)
• \(\displaystyle -(c+d)\)
• \(\displaystyle -\frac{1}{c+d}\)