Which of the Following Best Describes an Interval Estimate

Which of the following best describes an interval estimate?

A) It is a sampling procedure that matches each unit from population A with a "twin" from population B, so that any sample observation about a unit in population A automatically yields an associated observation about a unit in population B.
B) It is an estimate of a population parameter that is expressed as a range of values within which the unknown but true parameter presumably lies.
C) It is a sample statistic such that the mean of all its possible values equals the population parameter the statistic seeks to estimate.
D) It is the sum of an estimator's squared bias plus its variance.