Answer
The correct examples are a and c.
Work Step by Step
To convert a decimal to a percent, multiply by 100 and add a percent sign.
a) $0.231\times100=23.1\%\ \checkmark$
b) $5.12\times100=512\%\ X$
c) $3.2\times100=320\%\ \checkmark$
d) $0.0175\times100=1.75\%\ X$