If the number of admitted patients increased by 40 percent from March to August 2021 and also, 25 percent of the admitted patients were found Covid-19 positive in August 2021, what was the number of Covid-19 positive patients in August 2021?

The number of admitted patients in March 2021 = 900

By August 2021, the number of admitted patients are increased by 40% from March 2021 

= $$(100+40)\%\times\ 900$$

= $$(1.4)\ \times\ 900$$ = $$1260$$

Out of 1260 admitted patients, 25% are covid positive.

Hence the number of covid positive patients are =$$(25)\%\times\ 1260$$ 

=$$\frac{25}{100}\times\ 1260$$

$$\frac{1}{4}\times\ 1260=315$$ Patients.

Option (D) is correct.