Answer:
A crystalline solid
Explanation:
Most solids form with a regular arrangement of their particles because the overall attractive interactions between particles are maximized, and the total intermolecular energy is minimized, when the particles pack in the most efficient manner. The regular arrangement at an atomic level is often reflected at a macroscopic level. Liquids dont use to have this kind of arrangements or shapes.
Methanoic acid has a molecular formula of HCOOH, when form an ester it's HCOO-, so the rest of the ester is -C4H9, a saturated 4 carbon chain. As shown in the attached diagram, there are 4 structural isomers, and the third isomer has 2 stereoisomers. So the answers is D:5.