The correct choice is (d) Saccharomyces cerevisiae
The best I can explain: Saccharomyces cerevisiae is not used for the production of citric acid. It is mainly used in the production of beer as it is a brewers’ yeast. Aspergillus niger, Aspergillus wentii, Bacillus licheniformis, Candida oleophila, etc. are used in the production of citric acid.