What is the principle?

[Arcane Jill]

Hi,

Ignoring all compatibility characters; ignoring everything that has gone 
before; and considering only present and future characters (that is, 
characters currently under consideration for inclusion in Unicode, and 
characters which will be under consideration in the future), which of 
the following is the PRINCIPLE which decides whether or not a character 
is suitable:

(A) A proposed character will be rejected if its glyph is identical in 
appearance to that of an extant glyph, regardless of its semantic 
meaning, or
(B) A proposed character will be rejected if its semantic meaning is 
identical to that of an extant character, regardless of the appearance 
of its glyph, or
(C) A proposed character will be rejected if either (A) or (B) are true, or
(D) None of the above
?

Although this is a question about the future, no clairvoyance is 
required, since I am asking about the principle behind decisions, not 
about specific characters.
Jill