Answer:
The second "hashtag" starting from left.
Step-by-step explanation:
This is not notes. Instead, they are called "sharps" in musical terms. They play a black key next to the white keys (except E sharp and B sharp). If you read from left to right, you would read them as:
F sharp (or fa) : the second highest sharp or the first one starting from the left side, closest to the grand staff. It is on a line.
C Sharp (or do): Next to fa. It is on a space.
G sharp (or sol): It is the highest compared to the others. It is above the highest line.
D sharp (or re): Second to the highest line.
A sharp (or la): the last sharp. It is on a space.
Note that if I say (or fa) and (or do) and etc, they are also on sharps, so youd read as DO SHARP. I was just too lazy to write them down.
But remember that they are not notes, they are sharps. And that they are on black keys.
But to answer your question, DO is BEFORE THE TWO BLACK KEYS. Do doesn't have any sharps nor flats, so you'd play them in white keys.