The right answer is B.
Taxis, is the phenomenon by which cells are attracted or repelled according to their environment.
It can be attraction and repellence. Finding food (eg glucose) while heading to its highest concentration is very important for bacteria, as well as avoiding harmful agents (such as phenol).
The terms "run" and "tumble" are used in chemotaxis with respect to the movement of cells in a container with a capillary tube containing an attracting or repelling agents.
