Answer:
answer I and III are true
Explanation:
a) True. Charges of the same sign ( + and + or - and -) repel each other
b) False. Electrons have negative charge , while protons (and also positrons) have positive change
c) True. Bigger amounts of charge have bigger electric fields. If we follow the equation for electric field
E= k*q/r²
where k= constant , r= distance to the other charge , q=charge
then higher the charge , higher the electric field
thus answer I and III are true