Which of the following is not a type of system?

biomedical

ecological

social

biological

(not sure if this is physics but it doesn't give me the option to pick science for subject)

Aballet student who learns with the of his instructor is demonstrating learning.

Two point charges are separated by a certain distance. how does the strength of the electric field produced by the first charge, at the position of the second charge, change if the second charge is doubled? a. the field does not change b. the field strength decreases by half. c. the field strength doubles d. the field strength quadruples

Which of the choices are parts of an atom? select all that apply. a.) compound b.) electron c.) neutron d.) molecule e.) photon f.) proton g.) element