The correct option is B 4, 5, 12, 15
In any proportion, the product of means equals the product of extremes.
product of means = 5×12=60
roduct of extremes = 4×15=60,
hence, 4, 5, 12 and 15 are in proportion.
Or in other words, we have 4:5::12:15.
Now consider the numbers 2, 3, 4 and 5.
2×5≠3×4.i.e., 10≠12, and thus these numbers are not in proportion.
Similarly, 3, 1, 9 and 1 are not in proportion (3×1≠1×9),
3, 4,6, and 4 are not in proportion(3×4≠4×6)