Answer
The answer is

Step-by-step explanation
As all the planets revolve in specific orbit around the sun. Then suppose these planets are in same line.
The distance of Mercury from Sun =

The distance of Earth from the Sun =

The distance of Mercury form The Earth = ?
⊕ ⊕ ⊕
Sun (A) Mercury (B) Earth (C)
B → A

C → A

C → B

C → B

C → B

C → B
