Which one is correct from the following [RPET 2001]

• A. \[\sin (ix)=i\,\sinh \,x\]
• B. \[\cos (ix)=i\,\cosh \,x\]
• C. \[\sin (ix)=-i\,\sinh \,x\]
• D. \[\tan (ix)=-i\,\tanh \,x\]