What For metallic structures, does the packing efficiency (see Sample Exercise 12.1) increase or decrease as the number of nearest neighbors (the coordination number) decreases?

i'm assuming that the correct answer is indeed the first one/ "a"..

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

hope i !