Octopus and squid have chemoreceptors on their
heads
tongues
tentacles
eyes

Octopus and squid have chemoreceptors on their tentacles. The correct option among all the options given in the question is the third option. The chemoreceptors present in the tentacles, not only helps the octopus and the squid to locate their food, but also to sense the coming of their enemy. 

trying to find the answer to this question aswell.