The function $f(x)=\frac{e^{|x|}-e^{-x}}{e^x+e^{-x}}+\cos ^3\left(\frac{x}{2}\right)$ from $R$ to itself is

• A

  An injective function
• B

  A surjective function
• C

  An even function
• Correct answer
  D

  Not bijective

Hence, the correct answer is option: 'D'.