Vishakhadatta exposed evils of the contemporary society by his satirical writings. There is no unanimity among the authorities on the date of Mudrarakshasa. However, majority of them are in favour of assigning the composition of this Sanskrit work to 4th–5th centuries AD. The Minister Signet’s Ring centres around the schemes of the wily Chankya to frustrate the plots of Raksasa, the minister of Dhanananda, the last ruler of the Nanda dynasty.

Vishakhadatta is the correct answer for the question as he exposed the evils of contemporary society through his satirical writings.

Below is a detailed explanation of the answer:

Introduction:
Vishakhadatta was an ancient Indian playwright and author who lived during the 5th century AD. He is known for his famous play "Mudrarakshasa," which is a political drama set in the times of the Maurya Empire. Through his writings, Vishakhadatta shed light on the corrupt practices and societal issues prevalent during his time.

Exposing Evils of Contemporary Society:
1. Satirical Writings:
- Vishakhadatta used satire as a literary tool to criticize the flaws and vices of the society he lived in.
- Satire is a form of writing that uses humor, irony, and exaggeration to expose and criticize societal issues.
- Through his satirical writings, Vishakhadatta aimed to bring about social change by exposing and condemning the evils of his time.

2. Mudrarakshasa:
- "Mudrarakshasa" is Vishakhadatta's most famous work, which showcases his satirical approach to addressing the societal problems of his era.
- The play revolves around the political intrigues and power struggles within the Maurya Empire.
- Vishakhadatta uses his characters and their actions to highlight the corruption, greed, and moral degradation prevalent in the society of that time.

3. Criticizing the Ruling Class:
- In "Mudrarakshasa," Vishakhadatta criticizes the ruling class and exposes their unethical practices.
- The play portrays the manipulative tactics employed by the political elites to maintain their power, often at the expense of the common people.
- Vishakhadatta's satirical portrayal of the ruling class serves as a critique of the prevalent socio-political system.

4. Portrayal of Characters:
- Vishakhadatta's characters in "Mudrarakshasa" represent different sections of society and their flaws.
- By depicting characters with negative traits such as greed, deceit, and lust for power, Vishakhadatta highlights the moral decay of the contemporary society.
- Through his satirical portrayal, he aims to expose the evils and provoke introspection among the audience.

Conclusion:
Vishakhadatta, through his satirical writings and specifically through his play "Mudrarakshasa," effectively exposed the evils of contemporary society. His use of satire to criticize the ruling class and highlight societal problems makes him an important figure in Indian literature and a voice against corruption and moral degradation.