To solve this problem, we need to identify the stage of meiotic prophase where terminalisation of chiasmata occurs. Let's analyze each stage:$\newline \bullet$Leptotene:$\newline$ - This is the first stage of prophase I, where chromosomes start to condense and become visible.$\newline$ - Terminalisation of chiasmata does not occur in this stage.$\newline \bullet$Zygotene:$\newline$ - During this stage, homologous chromosomes begin to pair up in a process called synapsis.$\newline$ - Terminalisation of chiasmata is not a feature of this stage.$\newline \bullet$Pachytene:$\newline$ - In this stage, crossing over occurs, where homologous chromosomes exchange genetic material.$\newline$ - Although chiasmata form here, terminalisation does not occur in this stage.$\newline \bullet$Diakinesis:$\newline$ - This is the final stage of prophase I, where chiasmata move towards the ends of the chromosomes, a process known as terminalisation.$\newline$ - This is the distinctive feature of diakinesis.$\newline$Therefore, the stage of meiotic prophase that shows terminalisation of chiasmata as its distinctive feature is Diakinesis.$\newline$This corresponds to Option 3.