so i personally think that the answer is -4.5.
my reason is that since point A is -7.7, and point C is 0, it has to be close to point A. since a negative that has a smaller number (ex: -3 > -8) is worth more than a negative with a bigger number, the answer can't be -9.2 or -8. now we're left with -4.5 and -1.3. Since -1.3 would be a closer point to 0, and B is pretty far from C, -4.5 is the most reasonable answer.
hope this helps !