How is a block design different from a randomized controlled trial with uncontrolled covariates?

Group of answer choices

A block design allows for early stopping rules, where you iteratively add subjects to your experiment.

A block design allows for the treatment to be randomly allocated within each of many levels.

A block design allows different treatment groups to be randomized so as to understand the interactions between different levels for different treatments.

A block design is the only way to apply Thompson sampling to use Bayesian inference.