| Function | Usage |
| 1. Noun | a. Still waters run deep |
| 2. Adjective | b. He wanted some stills for magazine |
| 3. Verb | c. The good news makes mestill my fears |
| 4. Adverb | d. Will you still love me when I am old and grey? |
Instead of starting from each grammatical function and finding its usage, we can go the other way, reading each usage sentence first and naming its function directly.
Reading the usage sentences first and naming their function confirms noun-b, adjective-a, verb-c, adverb-d, which is exactly the third option.
Let's summarize:
Therefore, the correct answer is 1-b, 2-a, 3-c, 4-d.