Answer:
It's a, 2^x + 3
Explanation:
If you look at the y-intercept, you can see that there was a vertical shift upwards by 3 (y intercept moved from y = 1 to y = 4).
If you're studying for the SAT, it'll be good to study the transformation rules, including horizontal stretches/shifts. They always seem to throw one or two questions about those on there.