A joint sitting of both Houses of Parliament can be called to discuss a bill that has been passed by one House but has been pending in the other House for a period of six months. This means that if one House passes a bill but the other House does not take any action on it for six months, a joint sitting can be convened to resolve the situation. During the joint sitting, both Houses come together to consider the bill and make a decision on it. It is important to note that this provision of a joint sitting is mentioned in the Constitution of India, and it allows for the resolution of a deadlock between the two Houses regarding the passage of a bill. No other options, such as four months, one year, or two years, are considered as the relevant period for convening a joint sitting.