Jawless fish probably evolved around:

The correct answer is Option (2) → 350 million years ago

The book gives a short timeline of life on earth in million years ago (mya). Each of these figures belongs to a different event.

Option (2) 350 million years ago — Correct. In the story of evolution, jawless fish probably evolved around 350 million years ago (mya). Sea weeds and a few plants also existed then.

NCERT Extract:
A Brief Account of Evolution – “… Slowly single-celled organisms became multi-cellular life forms. By the time of 500 mya, invertebrates were formed and active. Jawless fish probably evolved around 350 mya. Sea weeds and few plants existed probably around 320 mya. We are told that the first organisms that invaded land were plants.”