Consider a hot$-$air heating system. The control sub$-$system:

Receives information from three temperature sensors $(t1,t2$ and $t3),$ and from a temperature selector switch that set the desired temperature $($Tref$),$ and

Generates two signals: onoff $in\{ON,$OFF$\},$ that starts$/$ stops the heater, and flow $in\{OFF,$LOW,HIGH$\},$ that controls the hot$-$air outlet.

The functioning of the control sub$-$system is as follows: Every minute $...$

An average temperature Tavis computed as Tav$=0\mathrm{.}2(t1+t2)+0\mathrm{.}6t3$;

if Tav $$ Tref then onoffand flow are set to OFF;

if Tref$-1$ Tav $<$ Tref then onoff$=$ ON and flow $=$ LOW;

if Tav $<$ Tref$-1$ then onoff $=ON$ and flow $=$HIGH.Which of the following algorithms properly describes the functioning of this control sub$-$system?

loop

Tav$0\mathrm{.}2**t1+0\mathrm{.}2**t2+0\mathrm{.}6**t3$;

if $($Tref $-$ Tav$)0$ then onoff $$ OFF; flow $$ OFF;

else if $($Tref $-$ Tav$)1$ then onoff $0N$; flow $$ LOW;

else onoff $0N$; flow $$HIGH;

end if;

end if;

end loop;

loop

Tav$0\mathrm{.}2**t1+0\mathrm{.}2**t2+0\mathrm{.}6**t3$;

if $($Tref $-$ Tav$)0$ then onoff $$ OFF; flow $$ OFF;

else if $($Tref $-$ Tav$)1$ then onoff $0N$; flow $$ LOW;

else onoff $0N$; flow $$HIGH;

end if;

end if;

wait for $60s$;

end loop;

loop

Tav $0\mathrm{.}2**t1+0\mathrm{.}2**t2+0\mathrm{.}6**t3$;

if $($Tref $-$ Tav$)1$ then onoff $$ ON; flow $$ LOW;

else if $($Tref $-$ Tav$)0$ then onoff $<$ OFF; flow $$ OFF;

else onoff $0N$; flow $$HIGH;

end if:

end if;

wait for $60s$;

end loop;