In the course of evolution, life forms on earth tend to move from _____.

Water to land

The correct answer is Option (2) → Water to land

The passage explains the evolutionary transition from aquatic to terrestrial life. Life began in the oceans, so many of the earliest and most primitive organisms lived in water. Over time, as some species evolved to live on land, they had to develop new adaptations to survive in the different environment. These adaptations included internal reproduction (as opposed to external fertilization in water) and respiration through lungs instead of gills.

One of the key pieces of evidence for this evolutionary transition is the presence of gill slits during the embryonic development of land-dwelling organisms. Although these organisms do not have gills as adults, the presence of gill slits during embryonic development suggests that their ancestors once lived in water and used gills for respiration.

Therefore, when asked about the direction of evolution—whether it was from "water to land" or "land to water"—the correct answer is "Water to land." This reflects the evolutionary history where life began in water and later adapted to life on land.