Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Water is a very important part of the physical weathering of rock. Which of these properties of water is most important in causing some of the physical weathering of rock?
Water expands when it freezes.
Cohesion and surface tension.