X-gal substrate is also known as -

Question

( A ) Ethidium bromide
( B ) 3-chloro-5-indole-4-bromo-$\alpha$-D-galactosidase
( C ) 5-bromo-4-chloro-3-indole-$\alpha$-D-galactoside
( D ) $\alpha$-galactosidase