What's the difference between assert and assume?

$($a$)$

Dafny must prove both assertions and assumptions.

$($b$)$

Dafny proves only assertions, not assumptions.

$($c$)$

Dafny proves only assumptions, not assertions.

$($d$)$

Dafny proves neither assertions nor assumptions.

$($e$)$

A failed assertion causes subsequent asserts to act as if the failed assertion was true.