The correct answer is A) NHAI.
The National Highways Authority of India (NHAI) is a statutory body under the Ministry of Road Transport and Highways, Government of India. It is responsible for the development, maintenance and operation of national highways in India.
The KRDCL is a state-owned company that is responsible for the development and maintenance of roads in Karnataka. The BWSSB is a state-owned company that is responsible for the water supply and sewerage services in Bangalore. The BMTC is a state-owned company that is responsible for the public transport services in Bangalore.
The NHAI is the key organization responsible for the development and maintenance of national highways in Karnataka because it has the mandate to do so. The KRDCL, BWSSB and BMTC are not responsible for the development and maintenance of national highways.