The diagram below shows a horizontal beam of electrons entering a region between two charged plates. In which direction is the electron beam deflected?

Step 1: Identify the charge of the electron beam. An electron beam consists of electrons, which are negatively charged particles.

Step 2: Determine the direction of the electric field. The diagram shows electric field lines pointing from the positively charged plate (top) to the negatively charged plate (bottom). Therefore, the electric field is directed downwards.

Step 3: Determine the direction of the force on the electron beam. A negatively charged particle experiences a force in the direction opposite to the electric field. Since the electric field is directed downwards, the force on the negatively charged electron beam will be directed upwards.

Step 4: Conclude the deflection direction. The electron beam will be deflected in the direction of the force acting on it. Thus, the electron beam will be deflected upwards.

The final answer is $\boxed{D. Upwards}$ 3 done, 2 left today. You're making progress.