In the following passage some of the words have been left out. Read the passage carefully and choose the correct answer for the given blank out of the four alternatives.
We are (146) in a time of great and (147) changes. The most obvious (148) of the modern world is the (149) development of science and technology. This has given man a deeper (150) of nature.

• part (148)

• side (148)

• feature (148)

• nature (148)