Statement I is not correct: Mangroves grow in saline/brackish water — they cannot store freshwater for paddy cultivation in saline belts.
Statement II is not correct: Mangroves have salt-secreting roots/leaves; they do not convert saline water into freshwater.
Statement III is correct: Mangroves act as natural bio-shields against tidal surges and storm surges, and provide biomass/livelihood resources for coastal communities.
Source: https://www.sciencedirect.com/science/article/pii/S1385110123001181
https://www.downtoearth.org.in/wildlife-biodiversity/shrimp-salt-rice-can-help-save-mangroves-if-they-choose-to
The Notification for the Civil Services Examination, 2021 was released by the Commission on March 04, 2021. The notification contains all the details related to the examination dates, number of vacancies, eligibility criteria, syllabus, application process, fee, exam centers etc. The exam is being conducted to fill in 712 vacancies as listed in the notification with 22 vacancies reserved for Persons with Benchmark Disability. The Preliminary examination will be held on October 10 2021. Candidates can visit the Commission’s website  to fill the application form. Detailed instructions for filling up online applications have been provided on the website. The application window was closed on March 24 2021. The admit cards for the Preliminary Examination were made available from September 16 2021. The admit cards can be downloaded from the Commission’s website on the above mentioned link.