What characteristics do mutations have?

Question

anonymous · Answer

All have some validity, except "always harmful". Of the remaining choices, "occasionally beneficial" is the best (and it disproves "always harmful", but the common, unlisted "no impact" also does). 

 The others can describe some mutations, but are not qualified by "occasionally", "sometimes" or some other indication of non-universality: 
 omission of information -- lost bases or sequences 
 addition of information -- inserted bases or sequences 
 mistakes in copying -- sometimes the gene is damaged when replication is not in progress