reaktywny in English:

To be receptive to an idea or proposal. It is not the strogest of the species that survive, nor the most intelligent, but the one most responsive to change.

The patient was not responsive to the treatment.

Westminster needs to change. To be more responsive to the needs and demands of ordinary people, wherever they are in the UK.

The European Central Bank has been responsive and has acted well.

The audience was really responsive.

The employer was responsive to our safety concerns.

be responsive to sth

The disease has proved responsive to the new treatment.

It is not the strongest of the species that survive, not the most intelligent, but the one most responsive to change.

He was very kind and responsive.