In Time Series Databases (like Prometheus/InfluxDB), what is the 'Cardinality Explosion' problem?

1. A The physical exhaustion of local disk space caused by storing an excessive number of high-resolution data points per second for a single metric.
2. B The creation of too many unique label combinations (e.g., using `user_id` as a tag), which bloats the inverted index and exhausts system memory.
3. C A computational failure that occurs when timestamps exceed the 64-bit integer limit, causing the storage engine to incorrectly overwrite historical data.
4. D A specialized write-anomaly where data points arriving out of chronological order force the database to perform expensive, recursive re-indexing of the entire shard.