For question D, i read answer somewhere in gmatclub and other gmat prep courses, but i forgot the source. all i can say is that i read it from one of prep courses.
SC:
for 500 level questions, you should spend 30-40 sec
for 600-700 level questions, you should spend no more 45 sec - 1 min
for 700+ questions, you should spend 1:30
CR:
for 500 level questions, you should spend under 1 min
for 600-700 level questions, you should spend no 1-1:30 min
for 700+ questions, you should spend 2 min
RC:
short reading: 2 min for reading, answering questions around 1 min.
long reading: 3 min for reading, answering questions around 1 min.
quant:
for 500 level questions, you should spend around 30 - 45 sec
for 600-700 level questions, you should spend 1-1:30 min
for 700+ questions, you should spend 2 or more
you don't have to check time after every question you have done. you should check every 5 questions and below are the general timing you can examine if you are in pace.
Attachments

timing.PNG [ 23 KiB | Viewed 1486 times ]