Final answer:
The letter x represents two phonemes, /k/ and /s/, and occasionally represents /g/ and /z/.
Step-by-step explanation:
The statement 'The letter x is the only letter that stands for two phonemes, /k/ and /s/, and occasionally, /g/ and /z/' is True.
The letter 'x' represents the /k/ sound in words like 'box' and 'fox' and the /s/ sound in words like 'relax' and 'six'.
It occasionally represents the /g/ sound in words like 'exaggerate' and the /z/ sound in words like 'exam'.