What does each symbol on a
pedigree chart represent?

A pedigree results in the presentation of family information in the form of a facilely readable chart. Pedigrees utilize a standardized set of symbols, squares represent males and circles represent females.

i think that d. wind is the answer.   i missed the question when i answered a. currents.

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds