What is the function of ALE$/\frac{?}{\text{b}\text{a}\text{r}}($ PROG $)?$

It is an Address Latch Enable input pulse for latching the high$-$order byte of the address during accesses to external memory.

It is an Address Latch Enable output pulse for latching the low$-$order byte of the address during accesses to external memory.

It is an Adding Latch Enable output pulse for latching the low$-$order byte of the address during accesses to internal memory.

all of the above