The death of Charles I was significant because
A. He died without an heir
B. england became a democracy
C. He was tried and executed under the law
D. No one had ever killed a reigning monarch before

B. England became a democracy.

C. C. He was tried and executed under the law

Explanation:

Price Charles (1600-1649) was the king ruling England, Scotland and Ireland since 1625 to 1649. He was a very aggressive king who believes because he was a king that his decisions are final and no one could question his conscience.

The above looks to be the most significant on the death of Prince Charles during the period of 1649. During this period, the Monarchy form of government was abolished and replaced with democracy pending when Prince Charles's son take over in 1660.

The other point is that it became the first time a King was tried and executed under the law through the parliament.