A cell is infected by a virus, producing a signaling molecule, which diffuses to neighboring cells and triggers programmed cell death when the cells, in turn, are
infected by the virus. How you would classify this type of signaling?

the correct answer is moro reflex. this is usually witnessed in infants normally up to the age of 4-5 months (in some cases maybe more)  

it is caused by a sudden loss of support that makes the baby feel as if he or she is falling or is going to fall and hence the flinging of the arms and crying.