To solve this problem, we need to identify the conditions that favor the formation of oxyhaemoglobin at the alveoli. Let's analyze each condition:$\newline \bullet$High $pO_2:$ At the alveoli, the partial pressure of oxygen ($pO_2$) is high due to the fresh supply of oxygen from inhaled air. This high $pO_2$ promotes the binding of oxygen to haemoglobin, forming oxyhaemoglobin.$\newline \bullet$Low $pCO_2:$ The partial pressure of carbon dioxide ($pCO_2$) is low at the alveoli because carbon dioxide is being expelled from the blood into the alveolar air to be exhaled. A low $pCO_2$ facilitates the release of carbon dioxide from haemoglobin, allowing more oxygen to bind.$\newline \bullet$Less $H^+:$ A lower concentration of hydrogen ions ($H^+$) indicates a higher pH, which favors the binding of oxygen to haemoglobin. This is known as the Bohr effect, where a higher pH (less acidic environment) enhances oxygen binding.$\newline \bullet$Lower temperature:$$ A lower temperature at the alveoli also promotes the formation of oxyhaemoglobin, as haemoglobin has a higher affinity for oxygen at cooler temperatures.$\newline$Based on these conditions, the correct option is:$\newline$Option 1: High $pO_2,$ low $pCO_2,$ less $H^+,$ lower temperature.