In the Text Are the Following Conversion Factors

Multiple Choice

In the text are the following conversion factors:
i.1 mi = 1 609 m
ii.1 m = 39.37 in.
iii.1 ft = 30.48 cm
iv.1 in.= 2.54 cm
The 1 on the left hand side is assumed to have the same number of significant figures as the number on the right hand side of each of these equations.However,2 of these conversion factors are exact,and this means they have the equivalent of an unlimited number of significant figures when used in calculations.Which 2 are the exact conversion factors?

A) i and ii
B) i and iii
C) ii and iii
D) iii and iv