ΠωФ∉⊄⊅Ф⊃∅⊕⊥⊥∑∑∑ФπΔ Фπ⊂∅⊕

Which of the following are good safety measures during a thunder storm. a.) crouch with just the balls of your feet in contact with the ground. b.) rely on rubber-soled shoes to protect you. c.) stand under a tree. d.) go inside a closed building. e.) talk on a phone with a cord.