Which of the following is a sentence fragment?


a
Lisa Simpson won the presidential election in 2020 and was inaugurated in 2021.
b
In 2020, Lisa Simpson was elected, and he was inaugurated in 2021.
c
Inaugurated in 2021, Lisa Simpson had won the presidential election in 2020.
d
Lisa Simpson, who won the presidential election in 2020 and was inaugurated in 2021.