How and why does a Jubilee year cause Rosh Hashanah to take place on the 10th day of the month?
Ezekiel 40:1 reads "on Rosh Hashanah, on the tenth of the month". Rashi asks and answers, "'What “year” is it whose Rosh Hashanah falls on the tenth of the month? The answer is that this is the Jubilee year.'" From whom (or from what work) did Rashi source his answer?
How is it that the (or a) Jubilee year causes the following: "Rosh Hashanah falls on the tenth of the month"?
Note: I only have one question (as stated above), but I would like to know if the answer also answers the following: A. Is there a rabbinic opinion that the "Rosh HaShanah" mentioned by the Prophet Ezekiel refers to the first of Nissan? B. Is it ever possible that Rosh HaShanah again falls on the 10th of the month? C. Did Rosh HaShanah always fall on the 10th of the month during a Jubilee year?