Answer: A- a line
Explanation:
- A line is a one-dimensional term in geometry that has only length but not width.It extends up to infinity.
- A plane is a two-dimensional flat surface that extends up to infinity.
A plane is like a paper sheet , when we intersect a sheet by other sheet , we will observe that the intersection is a line ( as we given in the attachment).
Hence, the intersection of two planes is a line.
Therefore , the the correct answer is Option A - a line