Multiple choice: why have none of the competing hypotheses about the origin of life on earth been developed into a scientific theory?
another conflicting hypothesis that holds the answer has yet to be stated.
the hypotheses only disagree in whether self-replicating material was dna or rna.
these particular hypotheses are not testable.
the results of experimentation often yield conflicting data.

what is this saying?

you know that this symptom is misleading and quite often is related to: heart attack

a heart attack is a condition that occurs when the blood flow that transports oxygen to the heart muscle is damaged or cut off completely. the coronary arteries that supply the heart muscle with blood flow can be blocked by the accumulation of plaque. also, when the plaque within the heart artery breaks, it creates blood clot that can also hinder the blood flow. men that are over 45years of age and women that are over 55years of age are at risk of having a heart attack. the symptoms of a heart attack include chest discomfort, chest pain, coughing, and shortness of breath.