Which of the following is a pasture grass?

The pasture grass among the options given is Cynodon dactylon. This is because Cynodon dactylon, also known as Bermuda grass or African couch grass, is a well-known and widely used pasture grass that is native to Africa but is now found in many parts of the world. It is a highly valued grass because it is drought-tolerant, grows well in warm climates, and can withstand heavy grazing pressure. The other options listed are legumes that are often grown alongside grasses in pastures to improve soil fertility and provide additional nutrition for grazing animals.