I believe the answer is: No witness claimed to see Vanzetti during the shooting.
The defense lawyers hired by Vanzetti managed to obtain 16 witnesses who testify that they never see Vanzettin during the shooting. But the defense fail to convince the jury regarding his innocence, and Vanzetti eventually executed along with his partner for the robbery.
Nicola Sacco and Bartolomeo Vanzetti were Italian-born US anarchists who were convicted of murdering a guard and a paymaster during the armed robbery of the Slater and Morrill Shoe Company on April 15, 1920, in South Braintree, Massachusetts, United States, and were executed by the electric chair seven years later at Charlestown State Prison. Both adhered to an anarchist movement that advocated relentless warfare against what they perceived as a violent and oppressive government.The police took Sacco and Vanzetti into custody primarily on the basis of two pieces of evidence. Sacco and Vanzetti were indicted on September 11, 1920, for the murders and the Robbery. right option is B hope it helps
The purpose was to limit the freedom of African Americans and ensure their availability as a cheap labor force after slavery was abolished during the Civil War