According to IS specifications, the compressive strength of ordinary Portland cement after three days should not be less than A. 7 MPa B. 11.5 MPa C. 16 MPa D. 21 MPa

The correct answer is A. 7 MPa.

According to IS 456:2000, the minimum compressive strength of ordinary Portland cement after three days should not be less than 7 MPa. This is to ensure that the concrete is strong enough to withstand the loads that it will be subjected to.

Option B is incorrect because the minimum compressive strength of ordinary Portland cement after three days should not be less than 7 MPa.

Option C is