If an experiment has 5 factors and no replicates for a 2-level Experimental Design with...

The Main Effects for the 5 factors are not aliased or confounded but the 2-way interactions are confounded with the 3-way interactions

The Main Effects are confounded with only 4-way interactions

The Experimental Design is half-fractional

The experiment has 8 experimental runs with the first factor at the high level

The experiment has only 4 experimental runs with the 5th factor at the high level