US 10,915,021 B2  52  51  Of the recurring units ( c ), units having a hydroxyl group  or lactone ring are preferred, and units having a phenolic  hydroxyl group or lactone ring are more preferred.  In a more preferred embodiment, the polymer may further  comprise recurring units of at least one type selected from  recurring units represented by the following formulae ( dl) to  (d3), which are also referred to as recurring units (dl) to  (d3).  (dl)  (d2)  -continued  -continued 