Consider a language which uses the following set of characters:

Prefix set: aei

Small set: bcd

Large set: BCD

Punctuation set: xy

i$.$ A series must start with a prefix character

ii$.$ A series must end with a punctuation character

iii. A series can have up to but no more than $7$ characters, excluding prefix and punctuation characters.

iv$.$ A series may not have more small characters than large characters, unless the series has a small character that immediately precedes the final punctuation character

Which one of the following series do not follow all the rules of the language defined above?

aBdByy

acDDxe

iBCBCx

eecDx