Answer:
06 Hours
Step-by-step explanation:
As per the details given in the question it self, the neutron star X-1 is revolving around its companion star. The orbital period is 1.7 years which means it will complete the revolution in 1.7 years. During the movement in the orbit we will be able to detect the x-rays except for the time when it goes behind the companion star and eclipsed by it as seen from Earth.
Since the x-rays disappear completely for around 6 hours. This clearly means that eclipse period is 06 hours.