The answer you are looking for is B. Bubbles form when two chemicals are mixed together.
It is a natural emulsifier. An emulsifier keeps liquids in the mix from separating, such as oil and vinegar.
A Intron is a segment of a DNA or RNA molecule which does not code for proteins and interrupts the sequence of genes. A exon is An exon is any part of a gene that will encode a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. Hope this helped:)