Choosing a trend line vs a slope view

"How did X change between A and B?" is ambiguous. Two charts answer two different questions, so clarify before you build unless the user already named one:

• Change over time (line) — the value at every interval across the range. Shows the path: dips, spikes, when it moved. This is the default trend.
• Start vs end (slope) — only the first and last point, one line per series connecting them. Shows the net change and, across many series, which rose, which fell, and any rank flips — without the noise of the path between.

When the request could be either, ask a short either/or, e.g.:

Do you want to see how it moved across the whole period (a line chart), or just the change from the start to the end (a slope chart)?

If the user clearly wants one — "just tell me how much it grew start to end" → slope; "show me the trend / when did it spike" → line — skip the question and build it.