How is democratic government accountable, responsive …

Accountability:
The people form the government by electing their representatives therefore, in a democracy the government is expected to cater to the needs and expectations of the people. The people have the right to and the medium to examine the decision making process i.e there is transparency. In this way the government is accountable. 

Responsive:
Because it is a people's government, they have to cater to the needs of the people. This is usually something that non democratic governments lack in. Because there happens to be transparency, the people examine the process and this makes the government look after the needs and take measures to fulfil it

Legitimate: 
In any Democratic country there is has to be  formal constitution that is the binding force. It keeps the powers of government to the limited. Also while making decisions, the government has to follow norms and rules that make sure even though the decision process is long the decision made is more acceptable by the people