What roots absorb water more efficiently? endodermis, fibrous root systems, root hairs, vascular cylinders

The correct answer is root hairs

Reason -

The roots hairs are most important in the process of water absorption through soil as the root hairs are the basic contact point through which root connects to the soil. The root hairs increases the surface area of roots for  contacting  the soil and there by reduces the distance through which ions or water need to travel to reach the root surfaces. Root hairs being thin are capable to penetrate into deep soils which further is an added advantage.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.