Rank data in a table within categories based on date

[ashgov]

I need to rank data based on entry date and 2 category columns. I am working with 4 columns , a date column, Category Column 1 which has option A or B , Category Column 2 which has sub categories and the rank column. The sub categories are added to the table when Category Column 1 = B

I would like the rank function to only apply when Category Column 1 = A and rank within a sub category with 1 being the earliest entry for that sub category.

Thanks