Answer:
To be civilized and cultured
Step-by-step explanation:
The verb to cultivate has most of the listed meanings:
- to prepare and use land for crops or gardening;
- to grow a particular crop;
- also: to try to develop or improve something (e.g. cultivate a certain image).
The verbs to nurture and to cultivate are similar, but you usually use to cultivate when it comes to plants or crops and to nurture when it comes to people or animals.
In the given sentence, we have an adjective cultivated, which is derived from the verb to cultivate, but it has a different meaning: civilized, cultured, well educated, refined. When we're talking about someone's voice, that is the only meaning out of the listed ones we can use. So, the correct option is the third one.