To determine the value of cos2550, cos2350, sin2650, and sin2250, we need to use the unit circle and the properties of trigonometric functions.

1. Cosine of 2550:
To find the cosine of 2550, we need to locate the angle 2550 degrees on the unit circle. Since the unit circle is divided into 360 degrees, we can subtract 360 from 2550 to get an equivalent angle within one full rotation:

2550 - 360 = 2190 degrees

Now, locate 2190 degrees on the unit circle. The cosine value is the x-coordinate of the point on the unit circle corresponding to the angle. From the unit circle, we can see that the x-coordinate at 2190 degrees is 1. Therefore, cos2550 = 1.

2. Cosine of 2350:
Similarly, we need to find the equivalent angle within one full rotation for 2350 degrees:

2350 - 360 = 1990 degrees

Locate 1990 degrees on the unit circle. The x-coordinate at 1990 degrees is -1. Therefore, cos2350 = -1.

3. Sine of 2650:
To find the sine of 2650, we need to locate the angle 2650 degrees on the unit circle. Again, find the equivalent angle within one full rotation:

2650 - 360 = 2290 degrees

Locate 2290 degrees on the unit circle. The y-coordinate at 2290 degrees is 1. Therefore, sin2650 = 1.

4. Sine of 2250:
Similarly, find the equivalent angle within one full rotation for 2250 degrees:

2250 - 360 = 1890 degrees

Locate 1890 degrees on the unit circle. The y-coordinate at 1890 degrees is -1. Therefore, sin2250 = -1.

Hence, the correct values are:
cos2550 = 1
cos2350 = -1
sin2650 = 1
sin2250 = -1

None of the given options (a, b, d) matches these values, so the correct answer is option 'C' (2).