The primary law enforcement agency in Andhra Pradesh is:

Andhra Pradesh Police
Central Reserve Police Force (CRPF)
Indian Army
Border Security Force (BSF)

The correct answer is: a) Andhra Pradesh Police.

The Andhra Pradesh Police is the state police force of Andhra Pradesh, India. It is headed by the Director General of Police (DGP), who is appointed by the state government. The DGP is assisted by a number of Additional Directors General of Police (ADGPs), Inspectors General of Police (IGPs), and Deputy Inspectors General of Police (DIGs).

The Andhra Pradesh Police is responsible for law enforcement and public safety in the state. It has a number of specialized units, including the Criminal Investigation Department (CID), the Anti-Terrorism Squad (ATS), and the Special Protection Group (SPG).

The Central Reserve Police Force (CRPF) is a paramilitary force of India. It is the largest paramilitary force in the world, with over 320,000 personnel. The CRPF is primarily tasked with internal security, but it has also been deployed in counter-insurgency operations and peacekeeping missions.

The Indian Army is the land-based branch of the Indian Armed Forces. It is the largest standing army in the world, with over 1.4 million personnel. The Indian Army is responsible for the defense of India against external threats.

The Border Security Force (BSF) is a paramilitary force of India. It is primarily tasked with guarding the India-Pakistan and India-Bangladesh borders. The BSF has over 250,000 personnel and is one of the largest border guarding forces in the world.