A major consequence of invisible trade is that eventually the amount of invisibilities will exceed the payments for them. This means that the goods and services provided will be given, but payment for them is often neglected. This leads to a devastating deficit in funds. So the person or business supplying the goods can be in ruin, along with the person or business owing the money. This could threaten the economic strength of Texas.
The correct answer is - A. Cecil Rhodes and Leopold II traveled into the interior, showing other European leaders that such journeys were advantageous.
Rhodes and Leopold II in a way opened the gates for the European leaders to have the desire and go to the interior of the African continent. It was not just because of the possibility to do so because the African tribes were by far disadvantaged technologically and military compared to the Europeans, but it was the treasures that the continent was offering and how easy was it to get to them and use them for trade and become wealthy. That lead to a major colonization of the continent by the European colonial powers, and they took full advantage of the natural resources Africa had to offer.
I would say A, they were very resourceful. Hope this helps.