Pls in 20 min.
which sentence does not contain any errors in comma usage?
a. mrs. walter, the new librarian, is from arizona
b. california the most populous u. s. state, was once part of mexico
c. my next-door neighbor walt, is also an excellent climber
d. have you seen, carrie my cousin, from pittsburgh?

a. Mrs.Walter, the new librarian, is from Arizona.

Explanation:

When the noun preceding the appositive provides sufficient identification on its own, we need to use commas around the appositive. The appositive the new librarian needs to be set off with commas as it is not essential to the meaning of the noun it belongs to (Mrs.Walter). So option A is correct.

All the other sentences contain errors in comma usage.

invention of the washing machine

in the past, people used sticks and stones or scrub boards to clean their clothing. as it was sweaty, backbreaking work, we owe a world of to james king because he created the model for the modern washing machine in 1851. the most important issue was that this machine cleaned clothes while a person cranked the handle. doing this made people who used it develop strong muscles in their arms. later, in 1908, alva j. fisher created an electric washing machine named thor. this one was not the first automatic washing machine. however, it was one of the most popular models at the time.