Final answer:
The last sound in "switch" is /tch/, spelled with the letters 'tch,' which is one of the three common spellings of the /ch/ sound. The correct option is C.
Step-by-step explanation:
The last sound in the word "switch" is /tch/, which is represented by the letters tch at the end of the word. This particular sound is one of the three common ways of spelling the /ch/ sound, alongside ch and t when it comes before certain vowels. While other spellings such as sh, sch, and ch can represent the sound /sh/, they do not apply in this case.
It's important to note that approximately two-thirds of the time, the /ch/ sound is spelled as ch or tch, with ch being about five times as common as tch. However, in words like "switch," the spelling tch is used to represent the /ch/ sound at the end of the word. As a result, the correct answer to the question is option c./ch/.