What frustrations led workers like henryka kryzwonos in poland to demand an independent union? what tactics did they use to protest

The workers in Poland had a miserable life . They were having no civil liberties, no control over factories, no right to strike, low wages etc. Trade Unions did not protect their rights or work for their welfare as they were controlled by Communist Party. So these trade unions used to enforce the rule of the Govt. which led workers like Henryka Kryzwonos to strike and demand an Independent Union.

The workers began to protest in 1980. The tactics used by them include sit-in strike at shipyards, shutdown of railway traffic and most importantly "Solidarity" which brought a revolution in the history of Poland.

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.

the answer is actually b.   as habitats are destroyed, animals and plants may become extinct.   , according to edge nuity