Sample selected as a representative of population.

Greetings Tutor i hope you are doing well.

There is a MTQ in Exam Kit of Kaplan related to Viola & Co.
One of the question in the case is that

“The audit manager has asked you to review the results of same statistical sampling testing, which resulted in 20% of the payables balance being tested. The testing results indicate that there is a $45,000 error in the sample: $20,000 which is due to invoices not being recorded in the correct period as a result of weak controls and additionally there is a one-off error of $25,000 which was made by a temporary clerk”

Q) What would be an appropriate course of action on the basis of these results?
a) The error is immaterial and therefore no further work is required
b) The effect of the control error should be projected across the whole population
c) Poppy Co should be asked to adjust the payables figure by $45,000
d) A different sample should be selected as these results are not reflective of the population.

Although i was quite comfortable with Option B (Projecting the error to entire population except for anomaly) until my attention was drawn by Option D.
ACCA’s technical article on Sampling mentions that “if the auditor tests only 20% of trade receivables for existence at the reporting date by confirming after-date cash, this is hardly representative of the population, whereas, say, 75% would be much more representative”.
So based upon this can the 20% trade payable sample is also not a true representative of the population making Options D right as well ?