If RVR is not observed, what is provided in its place in the METAR report?

When the Runway Visual Range (RVR) is not observed, the METAR report will simply not include the RVR information, resulting in the omission of the group and the preceding space that would normally contain this data. This means that if RVR is not reported, there will be no mention of it in the METAR, and the formatting of the report will reflect this absence.

The other choices do not accurately reflect the handling of RVR data in METAR reports. For instance, visibility is not replaced with a standard value, nor is there a requirement to indicate the data source just because RVR is absent. Similarly, wind information remains unaffected by the absence of RVR, as it is reported independently of visibility conditions. Therefore, the correct answer captures the precise method of reporting when RVR data is not available.