Answer:
see below
Step-by-step explanation:
A <em>regular tessellation</em> involves repeated use of a single regular polygon to cover the plane.
A <em>semiregular tessellation</em> involves repeated use of <em>two or more</em> regular polygons (in the same order around each polygon vertex) to cover the plane.
The first and third diagrams do not involve regular polygons. The fourth involves only a single regular polygon. Hence the second diagram is the one of interest.
