Silent Hallcreeper

Silent Hallcreeper copies exactly what was printed on the target creature and nothing else (unless that creature is copying something else or is a token; see below). It doesn't copy whether that creature is tapped or untapped, whether it has any counters on it or Auras and Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on.

The phrase "that hasn't been chosen" refers only to that specific Silent Hallcreeper. If Silent Hallcreeper leaves the battlefield and then returns to the battlefield later, it will be a new object with no memory of the modes that were chosen when it was last on the battlefield.

If the copied creature is a token, Silent Hallcreeper copies the original characteristics of that token as stated by the effect that created that token.