The reason for this is that part of Namibia is taken up by the Namib desert, and also elsewhere Namibia suffers a lack of water, and it is one of the driest places in Africa. In some areas of Namibia ground water is for example available only during some and not all months of the year.
The correct answer is - lumber.
The lumber is both renewable and inexpensive resource, and it also can be found in every continent, apart from Antarctica. Still, the usage of lumber has to be managed carefully and with nice planning, because so far, the usage of lumber is surpassing the trees being planted to replace them, and that led to the total destruction of lots of forests throughout the world. This is a very easy thing to do, so the authorities have to force the companies in this industry to replant the areas from where the trees are cut, thus to have a proper usage of it, stable reserves, and protect the environment.
