Why lack of gravity might cause muscles to weaken

Since everything is “lighter” in space due to the lack of gravity, you don’t need as much strength to do things so your muscles begin to deteriorate and weaken because you aren’t maintaining your strength.

Iwould say a is correct

Adescription of  congestive heart  failure, its symptoms, risk factors, and treatment. to the  heart muscle  other than by artery or blood  flow  problems; signs of  heart  failure may not  meanthe patient has  heart  failure and they quit alcohol, or at least consume alcohol within the national recommended  limits.