These are two similar sounding names with similar sounding functions. When asked we often tend to mix up the function. Lets see the functions.

Carotid Body - Chemoreceptor (senses the O2 concentration in the blood)
Carotid Sinus - Baroreceptor (senses the blood pressure in the arterial system) (baro  = pressure)

Remember,
Carotid SinuS = senses 'blood preSSure' = Baroreceptor

So, the other will be chemoreceptor.