Both international & inland which procedure(s) shall be used to determine risk of collision?
a) long-range radar scanning
b) systematic observation of objects detected by radar
c) watching the compass bearing of an approaching vessel
d) all of the above

Option D: All of above.

is the correct answer.

Risk of Collision can be defined as a chance when two different bodies start bearing same position after some time of following some courses/situations.

In order to determine risk of collision, many procedures are used. Some of them include procedures like Long-range radar scanning, Systematic observation of objects detected by radar and watching the compass bearing of an approaching vessel are used.

According to Rule 7 (Risk of Collision):

All accessible sources that are right according to the faced circumstances shall be used for each vessel so that the collision risks (if any) are determined easily.

this seems to be in the wrong category. but i'll take some free points my dude

posting this in wrong category will result in people seeing it who won't know the answer.