Mark the letter A, B, C, or D to indicate the underlined part that needs correction in each of the following sentences.

The teacher explained of her students the importance of preserving cultural identity
1. of
2. the
3. of
4. cultural
Don't forget to turn out all lights when the rooms are not in use.
1. forget
2. out
3. when
4. in
I was finding an interesting biography while I was looking around the bookshop.
1. was finding
2. while
3. around
4. bookshop
When I was arriving at my grandparents' house, they were watching a programme about the customs of ethnic minorities in Viet Nam.
1. was arriving
2. were watching
3. the
4. of
As the second longest river in the world, an Amazon flows through several countries in South America before emptying into the Atlantic Ocean.
1. the
2. an
3. in
4. the
When my father studied in the UK, he also learnt to play a guitar and performed in a band.
1. the
2. a
3. performed
4. a
After graduating from university, my brother applied to more than five jobs before he was invited for his first job interview.
1. from
2. to
3. for
4. interview
My brother dropped out of school at 15, that made it harder for him to find a job.
1. out
2. at
3. that
4. for