D I’m 50% sure I searched it up 2
The answer is 24. you round up.
B. Only Sequence B
The one with the reflection over the line HI and then the 6 unit translation to the right
That's a 33% increase.
I calculated this using the formula:

Where n = the new value (16 in your question), o = the old value (12 in your question) and the result is outputted as a percent increase. You can check that this is correct by finding 33% of 12, adding the result to 12, and checking that the result equals your "new" number.
Note that 33% is only an approximation as your question requires a number rounded to the nearest whole.