英语和逻辑高手进!

英语和逻辑高手进!
I live alone,but today I have invited friends to dinner.I want everything to be ready to
serve at 1 pm.I have made a checklist of everything I need to do before then,together
with timings,as follows:
Prepare meat 10 mins
Cook meat (hot oven) 2 hours
Carve meat 5 mins
Prepare vegetables (potatoes,carrots,broccoli) 20 mins
Boil water for vegetables 5 mins
Boil vegetables 15 mins
Prepare gravy (using juice from meat after it has been cooked)5 mins
Prepare bread dough 20 mins
Bake bread (medium heat oven) 1 hour
Set table 15 mins
My gas cooker consists of one oven and a four-ring hob.I want to serve the dinner as
soon as possible after the meat has finished cooking.
What is the latest possible time I can begin my preparations?
A 7.55 am
B 9.15 am
C 9.20 am
D 9.30 am
E 9.50 am