Step 1: Think of the fuse as doing two jobs at once, staying invisible during normal operation and being a deliberate weak link during a fault. Both jobs shape what material and connection the fuse needs.
Step 2: For the invisible-during-normal-operation job, the element must not heat up noticeably at rated current, which calls for a material with good conductivity, keeping its own resistance and hence its own heating small. That supports (B).
Step 3: For the deliberate-weak-link job, the element has to fail fast when current climbs, and the simplest way to guarantee that is to use a metal that melts at a low temperature so it does not take much extra heat to destroy it. That supports (A).
Step 4: Because the heating effect of current grows with the square of the current, a bigger overcurrent generates disproportionately more heat, so the element melts sooner as the fault current increases. This produces the inverse relationship between current magnitude and operating time, confirming (C).
Step 5: Since the whole point is to break the current path on a fault, the fuse must sit in the same current loop as the protected circuit, meaning it has to be wired in series, never as a side branch. This confirms (D).
Step 6: Every one of the four statements passes the check.
\[\boxed{\text{(A), (B), (C) and (D)}}\]