Identify Grammatical Errors Sentences

Each of the questions consists of a certain number of sentences. Some sentences are grammatically incorrect or inappropriate. Select the option that indicates the grammatically correct and appropriate sentence(s).

1. People have good reason to care about the welfare of animals.
2. Ever since Enlightenment, their treatment has been seen as a measure of mankind's humanity.
3. It is no coincidence that William Wilberforce and Sir Thomas Foxwell Buxton, two leaders of the movement to abolish the slave trade, helped found the Royal Society for the Prevention of Cruelty to Animals in 1820s.
4. An increasing number of people go further: mankind has a duty not to cause pain to animals that 
5. have the capacity to suffer.