Step 1:
Varāha is one of the incarnations of Lord Viṣṇu.
Step 2:
Varāha Purāņa mainly glorifies Lord Viṣṇu and his Varāha incarnation.
Step 3:
The Purāņa is not primarily associated with Śiva, Brahmā, or Śakti.
Step 4:
Therefore, the correct answer is:
\[
\boxed{\text{(1) Viṣṇu}}
\]