The question can be changed into a new form:
Which element has the most negative electron affinity, or attraction for electrons? halogens have the highest electron affinities, and thus are more attracted to the electrons in the Hydrogen atom than any element in their respective periods.
In this case all the following choices are in the same period, thus Cl or Chlorine is the answer as it is a halogen.
A scientist would most likely need to update her model when it no longer supports the latest results.
The scientists would do biological studies of how the protein breakdown and combines with the muscles the engineers with then create a delivery system to get the protein to the muscle quicker and more effectively