同一种蝗虫，生活在青草中的体色呈绿色，生活在枯草中的体色呈枯黄色，以达尔文进化论的观点，这是 [ ]

A．人工选择的结果

B．用进废退的结果

C．自然选择的结果

D．生存竞争的结果

A woman in labor shouts to the nurse, "My baby is coming right now! I feel like I have to push!" An immediate nursing assessment reveals that the head of the fetus is crowning. After asking another staff member to notify the physician and setting up for delivery, which nursing intervention is most appropriate（）

A. Gently pulling at the neonate’s head as it’s delivered.

B. Holding the neonate’s head back until the physician arrives.

C. Applying gentle pressure to the neonate’s head as it’s delivered.

D. Placing the mother in a Trendelenburg position until the physician arrives.