Step 1: Understand what "rate of growth" means here.
The graph plots length (vertical axis) against month (horizontal axis, 0 to 5). The rate of growth in a month is how much the length rises during that month. On the graph this is how steep the line segment is between two neighbouring months.
So we need Seeta's rise in each month, and then we look for the month after which that rise starts to fall.
Step 2: Read Seeta's line (the blue one with diamond markers).
From the graph, Seeta's lengths are:
Month 0: 50, month 1: 51, month 2: 52, month 3: 54, month 4: 55, month 5: 56.
Step 3: Find the growth in each month.
Growth in month 1: \(51 - 50 = 1\).
Growth in month 2: \(52 - 51 = 1\).
Growth in month 3: \(54 - 52 = 2\).
Growth in month 4: \(55 - 54 = 1\).
Growth in month 5: \(56 - 55 = 1\).
So the monthly growth goes \(1, 1, 2, 1, 1\). It rises up to the third month, where it reaches 2, and then drops back to 1 in the fourth month.
Step 4: Check the same thing in percentage terms.
Growth as a percentage of the length at the start of the month:
\[ \frac{1}{50} = 2\%, \quad \frac{1}{51} \approx 1.96\%, \quad \frac{2}{52} \approx 3.85\%, \quad \frac{1}{54} \approx 1.85\%, \quad \frac{1}{55} \approx 1.82\% \]
The peak is again the third month, and the rate is lower after it. So the answer does not depend on whether we use plain increases or percentages.
Step 5: Decide when the decline starts.
The rate is at its highest in the third month and is lower in the fourth month. So the decline in the rate of growth starts after the third month.
Step 6: Why the other options are wrong.
Option (1), second month: after the second month the monthly growth jumped from 1 to 2, so the rate went up, not down.
Option (3), fourth month: the rate had already fallen during the fourth month itself (from 2 to 1). After that it stays at 1, so it does not start to decline after the fourth month.
Option (4), never: the rate clearly fell from 2 to 1 after the third month, so "never" is false.
Final Answer:
Seeta's monthly growth is 1, 1, 2, 1, 1, so the rate of growth begins to decline after the third month. This is option (2).
\[ \boxed{\text{Option (2): Third month}} \]