resist? please help me decide🙏🏻

Okay so i need an A in A level biology to get into uni. From my AS exams I got a total of 290/300 ums. But i recently got my january exam results for unit 4, and I disappointedly got 92/120ums ( which is a b). I actually have no idea how this happened since I literally got an A* in my unit 4 mock. Anyways, in order for me to get an A overall, I'll need to get 98ums in total from unit 5 and 6. So it has to be at least 98/180 ums. So do you think I am in a confident position to get an A, or should I resist unit 4? Please give me your advice🙏🏻😔