Whifh of the following is true for the cell shown here?

Question

Zn(s) I Zn^+2 (aq) II Cr^+3 (aq) I Cr(s)

a> the electrons flow from the cathode to the anode

b) the electrons flow from the zinc to the chromium

c) electrons flow from chromium to the zinc

d) the chromium is oxidized

The correct answer is B, but I need a reasoning

How we Know the direction for the electron flow?