How does the Salt March explain whether or not Gandhi’s plan for non-violent tactics was successful?

yes. it was successful .

Explanation:

Gandhi choses to remove the tax from salt in non violent form . so he decided to approach satyagraha movement which is also know as Dandi March . the march, thousands of Indians followed Gandhi from his religious retreat near Ahmedabad to the Arabian Sea coast, a distance of some 240 miles.

c. the dred scott v. sandford case,