1.B without regular cardio workouts, you will have a very hard time breathing
2.B all of those CAN give accurate info, but gov. studies are best due to the amount of people they question
3.C the AHA does reliable experiments that proves helpful
4.D gov wellness sites usually give old or washed down advice
5.B if your muscles aren't used to physical activity, they will respond a bit more "aggressively" for lack of a better word
The backpack's main force that it it is exerting on the body's back and hips is coming from gravity, and can pull the spine downwards. This is why it's important to ear both straps.
