Choose from the given options, the pair of words which carry a relationship similar to :

Virtual : Real

The relationship between the words in the question pair Virtual : Real is that of antonyms (opposites).

Looking at the options:

Genuine : Sanguine represents a relationship of opposites in classical behavioral traits (Authentic/Grounded vs. Impulsive/Hot-blooded/Overly Optimistic).

Atmosphere : Hydrosphere are complementary components of the Earth's ecosystem, not opposites.

Air : Oxygen is a part-to-whole relationship (Oxygen is a component of air).

Human : Homo sapien is a relationship of synonyms (Homo sapien is simply the scientific name for a human).

Since Option 1 is the only pair that establishes an opposing/contrasting relationship, it best matches the analogy.