<span>The discovery of thornless plants was made around the turn of the 20th century. To name one such thornless plant, particularly, the Blackberry plant, the deviation from the thorned blackberry canes were discovered in the United States. Since then, several different thornless blackberry varieties have been cultivated for fruit gardens.</span>
I think that the statement is true
Oxygen is the final electron acceptor in the electron transport chain, which allows for oxidative phosphorylation. Without oxygen, the electrons will be backed up, eventually causing the electron transport chain to halt.
I think the correct answer from the choices listed above is option B. A modification of the leaves into the spine in a cactus plant can be seen The spines are modified leaves. It helps defend the plant and also reduce the surface area which helps limit loss of water.