Let's analyze each set of words for the different sound in the underlined parts:

1. **Words:**
a. un**i**form
b. com**pu**ter
c. stu**de**nt
d. ju**do**

The different sound is in **c. stu**de**nt**. The underlined part **"de"** contains a different vowel sound compared to the others which feature the sound [juː].

2. **Words:**
a. bed**s**
b. clock**s**
c. wall**s**
d. table**s**

In this case, there isn't a different sound in the underlined parts since all of them produce the same [s] sound. However, if referring to voicing, **c. wall**s** could be an option, but it still sounds similar. Generally, there is no distinctly different sound here.

3. **Words:**
a. tea**ch**er
b. **ch**ess
c. lun**ch**
d. s**ch**ool

The different sound is in **d. s**ch**ool**. In this case, the "ch" sound in **school** is pronounced as [k], while the others are pronounced as [tʃ].

To summarize:
1. c. c. stu**de**nt
2. No distinct different sound, but potentially c. wall**s** for voicing.
3. d. s**ch**ool