MacDonald who had spent much of his time     graduating from college backpacking round Europe,decided last year to settle down.

MacDonald who had spent much of his time______graduating from college backpacking round Europe,decided last year to settle down.

1. A.
   when
2. B.
   while
3. C.
   since
4. D.
   before

MacDonald who had spent much of his time     graduating from college backpacking round Europe,decided last year to settle down.