Question

What surprised the british at bunker hill?

Answer 1

The answer is D: how fast the colonists created an embankment

Answer 2

The british were suprised that 
#1: The US militia stood firm.
#2: Even though they had better training and such, they took more casualties than the Americans (even though they won)
#3: They couldn't take the hill the first few tries

These are just 3 reasons why the british were suprised (there are more)

hope this helps