Read the rule and choose the correct options to complete the sentences

The child was eating soup while his mother was making salad. (Past Continuous + Past Continuous)

Sam was riding a horse when the rain started. (Past Continuous + Past Simple)

1. I was brushing my teeth
   [when|while] my sister was making tea.
2. My mum was shopping
   [when|while] the telephone rang.
3. Sasha and Olga were studying at school
   [when|while] their puppy was sleeping.
4. My friends were skating
   [when|while] we had snow in the forest.
5. My cat was eating
   [when|while] I was taking a shower.