Consider the given statements and conclusions. Choose the option that logically follows from the statements.
Statements:

* No layer is a coat.
* All coats are deposits.
* All deposits are sheets.

Conclusions:
I. All coats are sheets.
II. All deposits can never be layer.

Let us analyze the statements using Venn sets:
1. No layer is a coat: The set of Layers and the set of Coats have no intersection ($\text{Layer}\cap \text{Coat}=\varnothing$).
2. All coats are deposits: The set of Coats is entirely contained within the set of Deposits ($\text{Coat}\subseteq \text{Deposits}$).
3. All deposits are sheets: The set of Deposits is entirely contained within the set of Sheets ($\text{Deposits}\subseteq \text{Sheets}$).

Now let us evaluate the conclusions:

* Conclusion I: All coats are sheets. Since all coats are inside deposits, and all deposits are inside sheets, it follows definitively that all coats are inside sheets ($\text{Coat}\subseteq \text{Sheets}$). Hence, Conclusion I is true.
* Conclusion II: All deposits can never be layer. This statement means that it is impossible for the entire set of deposits to be contained within layers ($\text{Deposits}⊈\text{Layer}$). Since all coats are part of deposits, and no coat can be a layer, that specific part of deposits (coats) can never enter the layer set. Therefore, the entire set of deposits can never be layers. Hence, Conclusion II is true.

Since both conclusions I and II are true, the correct option is D.