Final answer:
True, Ngo Dinh Diem was an unpopular and harsh ruler in South Vietnam. His oppressive regime, marred by religious persecution and electoral fraud, stoked national unrest and ultimately led to his downfall.
Step-by-step explanation:
The statement that Ngo Dinh Diem proved to be a harsh and unpopular ruler in South Vietnam is true. Diem's government was marked by repression and corruption, fueled by a refusal to hold promised elections and policies favoring Catholics over the majority Buddhist population. His regime carried out acts of persecution against Buddhists and students, which heightened unrest and ultimately led to his overthrow and assassination. The South Vietnamese government, under Diem's rule, was characterized by harsh crackdowns on dissent, corrupt practices, and discriminatory policies — all of which intensified the country's unrest and contributed to the South’s instability during the Vietnam War.
President Diem was responsible for the growing unrest in Vietnam due to his oppressive policies, fraudulent electoral process, and favoritism towards Catholics over Buddhists, leading to widescale protests and violent reactions against his rule.