So, the completed sentence is: "Each time a new problem cropped up, he rushed to his parents for advice." In this context, "cropped up" means to appear or arise unexpectedly. Therefore, option (a) is the correct choice.
62, 79, 98, 119, 142, 165
79, 152, 231, 314, 405, 500
128, 128, 64, 192, 42 , 240
15, 30, 30, 20, 10, 8
72, 36, 54, 135, 470.5, 2126.25
21, 23, 27, 35, 51, 87
18 45 90 235 450 1125 2250
...2, 6, 24, 96, 384, 1536, 6144
53, 57, 66, 82, 117, 143, 192
16, 36, 128, 768, 6144, 61440
