Stone axe.
Activity Two:
Explain in a paragraph how modern transportation may
have contributed to salt and sea shells becoming less
scarce and also lost its value in the highlands of PNG.

The value of salt and seashells decreased or was lost because back in the days where transportation was primitive it was very difficult to transport goods from one region to the other. In this example, salt was very valuable because many places couldn't have access to it by exploitation means so they had to trade it.

Explanation:

The reasons behind this are three. The first one is that in primitive times, transportation was not as fast, as cheap, and as effective as it is today or at least in recent times. So, it was expensive. The second is that certain goods can only be found in specific places. Making them valuable for places where they can't be found. The third one is that the risks surrounding the trade of expensive goods included death. So, once all of those were change through the improvement of transportation they lost value.

sounds good to me mate!

answer; strength of association;