Statements : All snakes are trees. Some trees are roads. All roads are mountains. Conclusions : I. Some mountains are snakes. II. Some roads are snakes. III. Some mountains are trees.

The correct answer is $\boxed{\text{E}}$. None of the conclusions follows from the given statements.

The first statement, “All snakes are trees,” is an example of a universal affirmative statement. This means that the statement is true for all members of the set of snakes. The second statement, “Some trees are roads,” is an example of a particular affirmative statement. This means that the statement is true for some members of the set of trees. The third statement, “All roads are mountains,” is an example of a universal affirmative statement. This means that the statement is true for all members of the set of roads.

To determine whether a conclusion follows from a set of statements, we can use a method called syllogistic reasoning. Syllogistic reasoning involves using two premises to form a conclusion. The premises are statements that are assumed to be true. The conclusion is a statement that follows logically from the premises.

In this case, the premises are:

1. All snakes are trees.
2. Some trees are roads.

The conclusion is:

1. Some roads are snakes.

This conclusion does not follow from the premises. To see this, consider the following example:

All dogs are mammals.
Some mammals are cats.

Does it follow that some cats are dogs? No, it does not. This is because the premises only tell us that dogs and cats are both mammals. They do not tell us that dogs are a subset of cats, or that cats are a subset of dogs.

Similarly, the premises in this case only tell us that snakes and trees are both living things. They do not tell us that snakes are a subset of trees, or that trees are a subset of snakes. Therefore, the conclusion that some roads are snakes does not follow.

The same reasoning can be applied to the other two conclusions. The conclusion that some mountains are snakes does not follow because the premises do not tell us that mountains are a subset of snakes. The conclusion that some mountains are trees does not follow because the premises do not tell us that mountains are a subset of trees.

Therefore, none of the conclusions follows from the given statements.