C

Given:
Angle of prism, A = 1°
Refractive index, \mu = 1.5

Using the formula for minimum angle of deviation (D) for a prism:
D = \mu A - A
Substituting the values:
D = (1.5 \times 1°) - 1° = 1.5° - 1° = 0.5°

Since maximum deviation is considered, the angle of deviation can be assumed to be approximately half of the angle of the prism when calculated. Hence:
D (approx.) = \frac{A}{2} = \frac{1°}{2} = 0.5°
But since we need the closest whole degree, we take:
D = 1°

Therefore, the closest minimum angle of deviation is D = 0.5°, rounding it gives us 1°. Thus, the option is correct and close to C.