Final answer:
The length of x[0] is 6.
Step-by-step explanation:
The given code is written in Java and represents a two-dimensional array named 'x'. The array 'x' has 6 rows and varies in the number of elements in each row. To find the length of the first row, we can use the code 'x[0].length'. Since the first row has elements 1, 2, 3, 4, 5, 6, the length of the first row is 6.