Each figure is made of straight lines through the centre. Work out how the third figure of every row is formed from the first two, then pick the missing figure.

The third figure keeps every line that appears in either of the first two, and a line found in both is simply drawn once (top row: flat and upright, plus upright, gives flat and upright). The bottom row's two figures together have three different lines: both slanting lines and the upright line, so the answer has exactly those three: (c). (a) drops the shared upright line, which the top row shows must stay; (b) keeps only the shared line and (d) adds a flat line that is in neither figure.