Answer: Most likely 1 or 4
Explanation:
They are heavier because they absorbed the water.
Adaptation is a phenomenon that is about adjusting certain features to environmental conditions. Ie. birds are adapted to flight as they possess wings, very efficient lungs etc. or tropical plants are adapted to high temperature and humidity as they modified their photosynthesis process. but if some creature is adapted to the specific habitat or conditions, it is hard for it to manage in another habitat/different conditions. ie. birds are fast in the air but on the ground they are quite weak and prone to predators' attacks.
To smell and feel surfaces and sense temperatures
Once the Earth was full of water (ocean) after volcanic activities the mainland became land ( sorry about my english i am hungarian and i am still learning the language )