F_CPU= 16000000= To set clock frequency as 16MHz
MS_DELAY= 1000= To set value 1000 as equivalent to 1 second

Registers Involved:
DDRC: Data Direction Register for Port C= 0xFF for output
PORTC: Port C Data Register= Data written here is observed in the corresponding output pins(Port C= pin 37:30)

in-built function used: _delay_ms()
This function takes in "compiler-time" constants as a parameter,which defines the delay in milliseconds