Which causal argument is stronger?

group of answer choices
a. three local coffee houses have experienced an uptick in business this quarter.
b. the cause of this welcome change appears to be the new poetry reading events each has added.
c. three local coffee houses have experienced an uptick in business this quarter.
d. the cause of this welcome change appears to be the new poetry reading events each has added.
e. because the poetry readings are the only possible cause all three coffee houses have in common, it must have been the cause.