This is a very easy question or I would say a 'basic one'.
Anyways, If you have asked then let me tell you that the answer is the option (a) True
Cell signalling is a process by which cells communicate and respond in a synergistic way to external stimuli. The process by which cells communicate is known by the name cell signalling. To carry out the activities in which an organism engages on a daily basis, it is essential that there be complex mechanisms and processes going on among the cells.