The correct answer is "1 only." The Agni-IV missile is indeed a surface-to-surface missile, which aligns with India's strategic emphasis on developing a credible deterrent through its Integrated Guided Missile Development Programme. However, statement 2 is incorrect, as the Agni-IV uses a two-stage propulsion system that includes solid and liquid fuels, and statement 3 is also inaccurate regarding its range; Agni-IV has a range of about 4000 kilometers, not 7500 km. Thus, understanding the specifics of the missile's design and capabilities is crucial in examining India's defense strategy and technological advancements in missile systems.