If those are the options, then your best bet for this question is
'yet'.
The other words would definitely not work in this sentence :)
The correct answer is - all of these contributed.
The sediments in the lagoons come from multiple different sources. The rivers and streams from the mainland, the sediments brought by the wind, and even the ocean waves that manage to get over the spit occasionally.
The biggest influence in the deposition of the sediments in the lagoons though is by the rivers and the streams from the mainland. They carry sediments with them constantly, and the amount of those sediments is also on a high level, in fact they bring in so much sediments that they have actually built the lagoon itself.
The wind and the ocean waves that manage to get over the spit have much lesser influence in the total deposition of sediments, but still they do in some part, and it shouldn't be put aside.
The combination of the three different sources, with different types of sediments brought to the lagoon by each of them, gives the lagoons a beautiful and unique appearance.
This consists of the movement of ideas from one point of origin over a large span of time. This has to include the complete absorption of ideas into society, not just partially.
To learn more about this:
https://study.com/academy/lesson/diffusion-of-innovation-theory-history-examples.html
Hope I helped!
Answer:
D) it takes millions of years to form
