Why was civic virtue an essential element of the constitutional Convention

It was an essential virtue because the members of the convention knew that without Civic Virtue, their government wouldn't hold together.

Explanation:

The constitutional Convention was formed to build the government up. In order to do that, they knew Civic Virtue was important due to the fact that they needed just people who wouldn't corrupt the system of government and tear it down.

did mary wollstonecraft believe was a natural ingredient for women’s happiness?

so you should go with

a. strong