1. I really appreciate you saying so.

2. I really appreciate your saying so.

(Which one is right?)

3.There's always a lot of traffic at this time of day.

4. There's always a lot of traffic at this time of the day.

5. There's always a lot of traffic at this time of a day.

(Which one is right among the three sentences?)

2 is correct; 1 is incorrect.

3 is correct; 4 and 5 are not.