I just need the simple answer ABC or D

Why reason best illustrates why hershey and chase chose to use viruses in their experiment?

In a classic experiment using pea shape, mendel conducted two separate genetic crosses. in the first cross the parent plants were “true breeding” for pea shape; one had round peas ( r )and the other had wrinkled (r). the first cross produced a filial 1 generation of all round peas. in the second cross, mendel bred plants from the filial 1 generation. this cross produced different results. out of approximately 1000 plants, about 75% were round and 25% were wrinkled.

Which greenhouse gas is emitted when burn fossil fuels for energy? a. nitrogen b. oxygen c. carbon dioxide d. helium