Each option requires the use of a hand signal.

The latter two options require the player to discard the city card.

Both options require huge efforts and are connected with a lot of expertise.

But that option required the missiles to fly at least 600 miles.

Special options (including additional system memory) required using expansion slots, of which four were available.

All other options required one or more changes at various locations.

The second option also requires a judgment as to intent.

This option requires commercial software and is not free of charge.

These options require money, and that is making life complex.

The option of nuclear propulsion is back on the table and would require a completely different approach.