Consider a complete Huffman table shown below, generated for some message,

Which of the following inferences is true?

The message contained up to $10$ unique characters

Characters A and E appear most frequently in the message

The longest root$-$to$-$leaf path in the Huffman tree from which the code is derived has a length of $7$

The Huffman tree from which the code is derived has two root nodes

We can derive the message's compression ratio from only the given information