A system is a group of organs that work together and provide an organism with an advantage for survival. It is the most complex organization in your body and the final level of the progression from cells to tissues to organs and then systems.
The biosphere is everything. the whole planet. so all of the above is right
A stimulus, the cockroach is sensed by your eyes.
Your eyes transmit nerve impulses from the optic nerve, the a group of sensory neurons, to the brain, the central nervous system.
In the brain, the impulse is then transferred by relay / association neurons to the motor neurons which signals the effector which is the muscle in your legs to contract, making you jump in shock
