The fluorescent dyes used in the liquid penetrant testing process are most active whenenergised with black light of what wavelengths? (Å stands for angstrom units)

The fluorescent dyes used in the liquid penetrant testing process are

1.	The fluorescent dyes used in the liquid penetrant testing process are most active whenenergised with black light of what wavelengths? (Å stands for angstrom units)
A.	2.0 × 10-7m (2000Å)
B.	2.5 × 10-7m (2500 Å)
C.	3.25 × 10-7m (3250Å)
D.	3.65 × 10-7m (3650 Å)
Answer» E.