Known parts	=	10 + 5 + 1/50 = 15 + 0.02 = 15.02
Missing part	=	15.12 - 15.02 = 0.10
As a fraction	=	0.10 = \(\dfrac{10}{100} = \dfrac{1}{10}\)
Check options: A) 5/10 = 0.5, B) 8/10 = 0.8, C) 3/10 = 0.3. None equals 0.10 (1/10).
The correct missing part is 1/10, which is not among the given options.