Major industrial centers like Ludhiana and Amritsar have witnessed significant:

Worker strikes and agitations
Peaceful labor negotiations
Government suppression of unions
Decline of manufacturing industries

The correct answer is: a) Worker strikes and agitations.

Ludhiana and Amritsar are two of the major industrial centers in India. They have witnessed significant worker strikes and agitations in recent years. These strikes have been caused by a number of factors, including low wages, poor working conditions, and the lack of job security. The strikes have had a significant impact on the economy of these cities, as well as on the lives of the workers involved.

Option b) Peaceful labor negotiations is not the correct answer, as the strikes in Ludhiana and Amritsar have been largely violent and disruptive.

Option c) Government suppression of unions is not the correct answer, as the government has not been directly involved in suppressing the strikes. However, the government has been criticized for not doing enough to address the underlying causes of the strikes.

Option d) Decline of manufacturing industries is not the correct answer, as the manufacturing industries in Ludhiana and Amritsar have actually been growing in recent years. However, the growth of these industries has not been enough to keep up with the demand for jobs, which has contributed to the strikes.