On June 16, 1976 the Soweto Students Uprising began (Soweto is a neighborhood of Johannesburg). Around 20,000 students went to the streets and made a peaceful protest opposing to Afrikaan as the official language for instruction in schools. The government's responde was violence, killing hundreds of students, as a result, the revolt spread through the whole country and carried on until the following year. These events changed the socio-political landscape in South Africa which main problem was the Apartheid.
With the options provided, the answer to the phrase that trade union differed from the labor unions is that trade unions were organized or formed by skilled workers or workers employed in the building while labor unions are group of workers regarding if skilled or not.
C, social services for immigrants