How many strands make up a dna double helix? ?

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.

a chair, a bed, and a toothbrush

explanation:

i was told this before by a teacher, so yeah