diff --git a/src/exercises/day-1/solutions-morning.md b/src/exercises/day-1/solutions-morning.md
index fce004c7..cd13ad56 100644
--- a/src/exercises/day-1/solutions-morning.md
+++ b/src/exercises/day-1/solutions-morning.md
@@ -7,3 +7,8 @@
 ```rust
 {{#include for-loops.rs}}
 ```
+### Bonus question
+
+It honestly doesn't work so well. It might seem that we could use a slice-of-slices (`&[&[i32]]`) as the input type to transpose and thus make our function handle any size of matrix. However, this quickly breaks down: the return type cannot be `&[&[i32]]` since it needs to own the data you return.
+
+You can attempt to use something like `Vec<Vec<i32>>`, but this doesn't work very well either: it's hard to convert from `Vec<Vec<i32>>` to `&[&[i32]]` so now you cannot easily use `pretty_print` either.
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