Based on the error rate of manually and electronically filed returns, the chances of making an error using manual instead of electronic is c. 400 times more likely.
This can be found as:
= Percentage error from manual returns / Percentage error from electronic returns
Solving gives:
= 20% / 0.05%
= 400 times
In conclusion, option C is correct.
Find out more on filing returns at https://brainly.com/question/27300507.
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