Hydrogen is one of the most important element in the universe（）it provides the building blocks from which the other elements are produced.

A. Those failing to stop online sale on time will not be penalized.
B. Those who intercepted money from lottery sale will be prosecuted.
C. There is no honesty and security problem in online lottery sale.
D. Buyer can tell legal websites from illegal ones easily.

A. that once grow
B. once they grow
C. they once grew
D. once grew