To determine the value of \( k \) and whether the transformation results in a stretch or a compression, we need to analyze the given transformations of the parabolas.
In general, the transformation of a function of the form \( f(x) = ax^2 \) can be affected by the coefficient \( a \):
- If \( |a| > 1 \), the parabola undergoes a vertical stretch.
- If \( 0 < |a| < 1 \), the parabola undergoes a vertical compression.
Since the value of \( k \) is not directly provided in your question, we can infer it if we assume \( k \) refers to the coefficient \( a \) of the transformed parabolas.
Given the options and focus on the value of \( k \):
- The only option that suggests \( k = 0.5 \) is 0.5; compression and 0.5; stretch.
Based on the definitions above, since \( k = 0.5 \) implies \( 0 < k < 1 \), it corresponds to a vertical compression.
Therefore, the correct response is:
0.5; compression.