Determine the target center of gravity (CG) position.

The CG limits are between 18 m and 22 m. The middle of these limits is:

$$CG_{target} = \frac{18 \text{ m} + 22 \text{ m}}{2} = \frac{40 \text{ m}}{2} = 20 \text{ m}$$

The initial moment of the aircraft is $M_{initial} \times CG_{initial}$.
When a mass $m$ is removed from position $X_{removed}$, the new total mass is $M_{initial} - m$, and the new CG is $CG_{target}$.
The moment equation is:

$$(M_{initial} - m) \times CG_{target} = (M_{initial} \times CG_{initial}) - (m \times X_{removed})$$

Given values:
$M_{initial} = 112000 \text{ kg}$
$CG_{initial} = 22.62 \text{ m}$
$CG_{target} = 20 \text{ m}$
$X_{removed} = 30 \text{ m}$

$$(112000 \times 20) - (20m) = (112000 \times 22.62) - (30m)$$ $$2240000 - 20m = 2533440 - 30m$$

Add $30m$ to both sides:

$$2240000 + 10m = 2533440$$

Subtract 2240000 from both sides:

$$10m = 2533440 - 2240000$$ $$10m = 293440$$

$$m = \frac{293440}{10}$$ $$m = 29344 \text{ kg}$$

The mass that must be removed is 29 344 kg.

Comparing this to the given options:
A) 8 680 kg.
B) 43 120 kg.
C) 16 529 kg.
D) 29 344 kg.

The correct option is D.

The mass that must be removed is:

$$\boxed{\text{D) 29 344 kg.}}$$