The correct option is "Volunteering is a good way to make friends, help the community, and feel good."
Parallelism is achieved when the same grammar pattern is used when listing ideas. In this example, the parallel structures are "make friends, help the community and feel good" since they all use the same grammar structure: verb+object.
In the rest of the options, there is a break in the pattern so no parallelism is achived.
Wallstreet crashed in 1929, bankrupting those who held stocks in buisnesses, and those buisnesses suffered. Banks failed and people were unemployed
The dustbowl followed after, thus contining the depression on longer. Dust storms bothered crops, and made living conditions harder.
Answer:
In order to express oneself in a formal way, correct grammar must be used, since it makes for a serious tone, that is, it shows whatever was written was done so carefully and seriously, as a sign of respect for the addressee. In formal writing, even abbreviations must be avoided, as well as contractions. Therefore, correct grammar is the way to go if you want to achieve a formal tone.