In the sculpture shown below, whom is Varaha or boar avatar of Vishnu rescuing?

Earth goddess.

The correct answer is Option 3 - Earth goddess.

The Varaha or Boar Avatar of Vishnu rescuing the Earth goddess.( Aihole (Karnataka) c. sixth century.)

More information about the sculpture:

The Varaha Avatar is one of the most iconic incarnations of the Hindu god Vishnu. The sculpture in Aihole, Karnataka, from the 6th century CE, beautifully depicts an epic tale.

The Legend:

The demon Hiranyaksha, a powerful being, challenged the gods and stole the Earth, plunging it into darkness and chaos. He hid the Earth beneath the primordial waters.
To restore order and protect the universe, Vishnu took the form of a boar, Varaha. With his mighty tusks, he dived into the ocean and fought Hiranyaksha.
After defeating the demon, Varaha lifted the Earth from the depths of the water, holding it aloft on his tusks. He then placed the Earth safely back in its rightful place in the universe.

The intricate carvings show Varaha, a colossal boar, lifting Bhudevi, the Earth goddess, on his tusks. The sculpture is a testament to the artistic skill and devotion of the ancient Indian sculptors.