Why would this IF statement yield unintended results?

A sendable data extension with a text field named ‘Balance’ contains the value S6.96 for a particular record.

The following AMPscript statement is included in an email:

IF (Balance > 6.00) THEN

SET @Result = ‘Balance is more than $6.00

ENDIF

Why would this IF statement yield unintended results?
A . The operands are not the same data type.
B. The comparison should use the < operator.
C. Balance is a protected keyword.
D. Double quotes should be used instead of single quotes.

Answer: D