The others are wrong it's B. Condensation
The first molecule is a sensible molecule having complete octet of each atom such as C, H and O whereas the second molecule having hydrogen present between the aldehyde and methyl group and thus showing hydrogen is making bond with aldehyde and methyl as well which is not possible because hydrogen only having one electron in its octet due to which it can only form a single bond by sharing its valence electron.
They were created with stone and wood and sometimes even bones, I hope this helped!
Liquid :) it goes directly from a solid to a gas. Have a nice day!