One student heated a metal wire to produce high speed electrons. when the electrons struck a metal target, waves were produced as shown in the diagram below.

The correct option is A.
Looking at the given diagram, you will notice that the waves produced is in a direction which is perpendicular to the motions of the electrons. Waves that behaves in this way are called transverse waves and examples are ripples on water surface, vibrations in strings and electromagnetic waves.

The best description is: . nobody has any idea what q is.