You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Vehicle exhaust contains a form of pollution called particulate matter. Technologies are being developed to reduce the amount of particulate matter in exhaust. A vehicle that produces less particulate matter would have the greatest impact on which aspect of human health?  
 (A) heart health (B) respiratory health (C) the rate of birth defects (D) weight and physical fitness
B

The fossils of dinosaurs that lived millions of years ago can be found in  
 (A) the water of oceans. (B) the ice on ponds. (C) the trunks of trees. (D) rocks in the ground.
D

One end of a metal rod is placed over a flame during an investigation. A thermometer is touching the opposite end of the metal rod. Which best describes what is happening during this investigation?  
 (A) Convection carries heat to the thermometer. (B) Radiant energy warms the thermometer. (C) Mechanical energy from the flame carries heat to the thermometer. (D) Heat from the flame is conducted through the metal rod to the thermometer.

D