Why does the reaction rate decrease as the reaction progresses? O A. The temperature begins to go down.
B. The activation energy goes up.
O C. The rate constant changes over time.
O D. There are fewer reactants left to collide.

The reaction rate decreases as the reaction progresses, because there are fewer reactants left to collide.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later