What is the meaning of the designation ‘M30’ concrete suggested for a reinforced cement concrete work?

The mix characteristic compressive strength of 100 mm size cube at 28 days is 30 N/mm2.

The mix characteristic compressive strength of 150 mm size cube at 28 days is 30 N/mm2.

The mix characteristic compressive strength of 150 mm size cube at 365 days is 30 N/mm2

The mix characteristic compressive strength of 150 mm size cube at 28 days is 300 N/mm2

What is the meaning of the designation ‘M30’ concrete suggested fo

1.	What is the meaning of the designation ‘M30’ concrete suggested for a reinforced cement concrete work?
A.	The mix characteristic compressive strength of 150 mm size cube at 28 days is 30 N/mm2.
B.	The mix characteristic compressive strength of 100 mm size cube at 28 days is 30 N/mm2.
C.	The mix characteristic compressive strength of 150 mm size cube at 365 days is 30 N/mm2
D.	The mix characteristic compressive strength of 150 mm size cube at 28 days is 300 N/mm2
Answer» B. The mix characteristic compressive strength of 100 mm size cube at 28 days is 30 N/mm2.