Fill in the blank with the correct option: Parallelism is a principle used in _______, which states that 'All the rays drawn through various details should pass through the survey station.'

In survey work using a total station with reflector measurements, which of the following sequence of temporary adjustments must be performed at a station?

While carrying out a total station survey on one bank of a 250 m wide river, it is necessary to plot electric transmission posts on the opposite bank. No provision exists for crossing the river and the posts are inaccessible. In which mode should the survey work be done?