The correct answer is Rigveda.

• Vedas 
  • The Vedas are the earliest surviving literature of the Indian subcontinent.
  • There are four Vedas: the Rig Veda, the Sama Veda, the Yajur Veda, and the Atharva Veda.
  • Of these, the Rig Veda is the oldest and was composed about 3500 years ago. Hence, Option 2 is correct.
  • All the other Vedas are based upon it and consist to a large degree of various hymns from it.
  • It consists of a thousand such hymns of different seers, each hymn averaging around ten verses.
  • The Rig Veda is also the oldest book in Sanskrit or any Indo-European language. 

• Rigveda:
  • The oldest Veda is the Rigveda. It has 1028 hymns called ‘Suktas’ and is a collection of 10 books called ‘Mandalas.’ 
  • It is the oldest form of Veda and the oldest known Vedic Sanskrit text(1800 – 1100 BCE)
  • The meaning of the word ‘Rigveda’ is Praise Knowledge
  • It has 10600 verses
  • The meters used to form hymns are Gayatri, Anushtubh, Trishtubh, and Jagati (Trishtubh and Gayatri are most important)
• Samaveda:
  • Known as the Veda of melodies and chants, Samaveda dates back to 1200-800 BCE. This Veda is related to public worship. 
  • There are 1549 verses (except 75 verses, all have been taken from Rigveda)
  • There are two Upanishads embedded in Samaveda – Chandogya Upanishad and Kena Upanishad
  • The Samaveda is considered the root of Indian classical music and dance
  • It is considered as the storehouse of the melodious chants
• Yajurveda:
  • Stands to mean ‘Worship Knowledge’, Yajurveda dates back to 1100-800 BCE; corresponding with Samaveda. It compiles ritual-offering mantras/chants. These chants were offered by the priest alongside a person who used to perform a ritual (in most cases yajna fire.)
  • It has two types – Krishna (Black/Dark) & Shukla (White/Bright)
  • Krishna Yajurveda has an un-arranged, unclear, motley collection of verses
  • Shukla Yajurveda has arranged and clear verses
• Atharvaveda:
  • Stands to mean a tatpurusha compound of Atharvan, an ancient sage, and knowledge (atharvan+knowledge), it dates back to 1000-800 BCE.
  • The daily procedures of life are very well enumerated in this Veda
  • It has 730 hymns/suktas, 6000 mantras, and 20 books
  • Paippalada and the Saunakiya are two surviving recensions of Atharvaveda
  • Called a Veda of magical formulas, it includes three primary Upanishads – Mundaka Upanishad, the Mandukya Upanishad, and the Prashna Upanishad