1 and 2 are correct.
Megaliths were constructed either as burial sites or commemorative (non-sepulchral) memorials.
Megalithic culture, one which lasted from the Neolithic Stone Age to the early Historical Period (2500 BC to AD 200) across the world. In India, archaeologists trace the majority of the megaliths to the Iron Age (1500 BC to 500 BC), though some sites precede the Iron Age, extending up to 2000 BC. Megaliths are spread across the Indian subcontinent, though the bulk of them are found in peninsular India, concentrated in the states of Maharashtra (mainly in Vidarbha), Karnataka, Tamil Nadu, Kerala, Andhra Pradesh and Telangana.
According to archaeologists, around 2,200 megalithic sites can be found in peninsular India itself, most of them unexcavated. Even today, a living megalithic culture endures among some tribes such as the Gonds of central India and the Khasis of Meghalaya.

There are four linguistic groups in India: Austro-Asiatic (the oldest), Tibeto-Burman, Dravidian and Indo-Aryan (the most recent).

Only 1 is correct.
Lauriya Nandangarh is a historical site located in West Champaran district of Bihar. Remains of Mauryan period have been found here.
On excavation, Nandangarh turned out to be stupendous Stupa with a polygonal or cruciform base; with its missing dome which must have been proportionately tall, the Stupa must have been one of the highest in India This thirty-two-foot-tall column has an almost fifty-ton seated lion capital placed on its top, an engineering feat worth admiring.
The bull capital from Rampura is also another fine example of Mauryan sculpture. The village draws its name from a pillar (laur) of Ashoka standing there and the stupa mound Nandangarh (variant Nanadgarh) about 2 km south-west of the pillar.

Lai Haraoba is one of the main festivals still performed in Manipur which has its roots in the pre-Vaishnavite period. Lai Haraoba is the earliest form of dance which forms the basis of all stylised dances in Manipur. Literally meaning – the merrymaking of the gods, it is performed as a ceremonial offering of song and dance. The principal erformers are the maibas and maibis (priests and priestesses) who re-enact the theme of the creation of the
world.

2, 3 and 4 are incorrect.
Madhubani which means ‘forest of honey’, is a style of folk painting old enough to find mention in some of the ancient Indian texts like Ramayana. It is also known as Mithila, for its origin in the Mithila region in Bihar. Instead of contemporary brushes, objects like twigs, matchsticks and even fingers are used to create the paintings.
Since the paintings have been confined to a limited geographical range, the themes as well as the style are more or less, the same.
Madhubani is now found on apparel, paper, canvas, and other products, which boast of designs inspired by Hindu deities such as Krishna, Rama, Lakshmi, Shiva, Durga, Saraswati, all of whom have been painted in Madhubani since ancient times.