When we touch a van de graaff generator, our hair may stand up if it is dry. this happens only if the strands of our hair
a) acquire atoms.
b) repel each other.
c) attract each other.
d) gain negative charge.

B) repel each other.

Explanation:

The Van de Graaff generator works by generating net positive charges. Consequently, any material that comes in contact with the electrostatic generator ends up becoming positively charged.

When a human touches the generator, such human also becomes positively charged including every strand of hair on the person's head.

According to Coulomb's law of electric forces, like charges repel one another while unlike charges attract. Hence, the positively charged hair strands try to stay as far away from one another as possible in accordance with Coulomb's law which manifests as 'standing up of hair strands'.

The correct option is B.

"the periodic table is arranged in order of atomic number."