ASTRONOMY — Mean Earth–Moon distance (recognition). The Moon orbits Earth at an average (mean) distance of approximately:

Introduction / Context:
Knowing key Solar System distances enables quick order-of-magnitude checks. The average Earth–Moon distance is a frequently cited figure in space science and general knowledge.

Given Data / Assumptions:

• We need the mean (semi-major axis) Earth–Moon distance.
• Values are given in “million kilometres.”
• No conversion is required; select the closest standard value.

Concept / Approach:
The Moon’s orbit is elliptical, but the mean Earth–Moon distance is about 384,400 km, which is 0.3844 million km. Larger numbers correspond to planetary distances (e.g., Earth–Sun distance ~149.6 million km).

Step-by-Step Solution:
Recall standard value: ≈ 384,400 km.Express in million km: 0.384 million km (rounded).Compare with options; select 0.384 million km.

Verification / Alternative check:
Lunar laser ranging experiments consistently measure Earth–Moon distance around this value, with monthly variations due to orbital eccentricity.

Why Other Options Are Wrong:
149.6 million km — mean Earth–Sun distance (1 AU).579 million km — approximate mean distance of Jupiter from the Sun.227.9 million km — approximate mean distance of Mars from the Sun.1.496 million km — off by a factor of 100; confusion with AU scaled down.

Common Pitfalls:
Mixing lunar distance with astronomical unit or planetary orbital radii. Watch the units “million km.”

Final Answer:
0.384 million km