Water molecules tend to stick to one another by
ionic bonding
hydrogen bonding
covalent bonding

hydrogen bonding

Explanation:

Ionic bond is formed by the transfer of electrons between metals and non metals.

Covalent bond is formed by sharing of electrons between two non metals.

Hydrogen bond is the bond formed between hydrogen and an electronegative atom such as fluorine, oxygen and nitrogen.

Water molecules are bonded by strong hydrogen bonding between the hydrogen atom and the electronegative oxygen atom and thus are bonded by cohesive forces of hydrogen bonds.

organisms are more likely to be more preserved in mud than sand because mud is moist and wet, while sand is very dry.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current