Theo was doing research to support the claim that exercise increases heart and lung health. he had 50 people do a rigorous exercise program. each week, for six months, he tested their heart and respiratory rate. he determined that exercise does increase heart and lung health. which best describes his claim? a. it is valid because he used multiple trials. b. it is invalid because he did not have a control group. c. it is invalid because his sample size was small. d. it is valid because he controlled the exercise program.

Your answer should be A

Probably invalid.

Explanation:

Where is the control group? Everyone exercised.

explanation: magnetic pole, region at each end of a magnet where the external magnetic field is strongest. the south-seeking pole, or any pole similar to it, is called a south magnetic pole. unlike poles of different magnets attract each other; like poles repel each other.

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )