In the following question, out of the four alternatives, select the alternative which will improve the bracketed part of the sentence. In case no improvement is needed, select "no improvement".
I understood that we (is influenced) by what we see, what we hear.
Muscle cramping is a common problem encountered by athletes and non athletes alike. Defined as painful involuntary skeletal muscle contractions, cramps may be categorized as either non exercise related or exercise related. Traditionally, such cramping was believed to arise from dehydration, electrolyte imbalances (including magnesium, potassium and sodium),accumulation of lactic acid, or low cellular energy levels.